Musty, fishy, smoky, and even rotten odors are enough to kickstart a whole-home cleaning frenzy at first whiff. The only problem is that no amount of Mr. Clean or deep cleaning is helping to eliminate that pesky odor. So why does your house smell even if it’s clean?

Here’s the TL;DR:

Your house may smell even if it’s clean because the air is stale and needs a refresh. It’s possible your unwashed laundry is growing smelly bacteria, your carpets absorbed foul odors or spills, or your pets had an accident. There may also be hidden grime, mold, mildew, or rotting foods.

According to the American Cleaning Institute (yes, that’s real), 31% of us are unsure if we’re cleaning correctly, while 34% worry we’re not cleaning enough. But which of those—if any—is to blame for your home’s stench? Read on to learn why your house stinks, even after cleaning.

1. Your Home’s Air Is Stale + Musty

an open exterior window with wind blowing

Worrying that your house has a bad smell isn’t unusual. In fact, a OnePoll survey from 2022 found that 69% of us fear our house smells when hosting guests.

Sometimes, the source of the odor is simply stale air. A lack of ventilation and circulation can make a house smell musty.

This lack of fresh air can reduce indoor air quality by forcing the build-up of airborne pollutants, including:

Many describe stale air as having a musty or stuffy odor.

The simplest remedy to stale air is to open windows to draw fresh air in and open interior doors to improve airflow throughout the space. A fan, dehumidifier, or air purifier can help to pull these unpleasant smells out of the air and make it smell fresh.

2. Your Unwashed Laundry Is Growing Bacteria

dirty laundry in hamper

That pile of dirty laundry in your hamper could throw the entire household scent off-balance. As worn clothes and used bath towels sit unwashed, the odor causing bacteria they absorbed slowly release gases—and along with it—a blend of rancid odors.

Clothing fibers absorb sweat, dead skin cells, body oils, and a waxy substance known as sebum as you wear your clothes. The bacteria on your skin and in the fibers of your clothing break down these organic materials, including sweat and skin cells.

This process releases a range of odor compounds.

You have these to thank for that weird smell—sour, musty, or borderline buttery—in your laundry room. Damp towels and sweat-soaked clothes only worsen the odor, encouraging the growth of mildew and musty odors as they sit in the hamper.

To fix this problem, wash your dirty laundry more often. And don’t let washed clothes sit for longer than 8–12 hours in the washing machine to prevent the growth of mildew and mold.

3. Your Carpets Absorbed Foul Odors

close up of carpet fibers

Vacuuming and shampooing your carpet can successfully get rid of set-in odors from its surface. However, these odors and spills can become trapped in the carpet fibers and the layer of padding underneath (called the “underlay”).

These odors become much more stubborn to remove.

Absorbed moisture from leaks, spills, and humidity create a damp environment. This dampness is ideal for mildew and mold growth and also the source of that iconic musty carpet smell. The breakdown of spilled beverages and pet messes also releases some pretty gnarly odors. 

According to a survey of household guests (not my guests, just in general), two of the three worst household odors are cigarette smoke (58%) and pets (51%). 

Anything from a dumped litter box to a former owner smoking can force naturally porous carpeting to absorb these smells. Once absorbed, they may trigger a relentless whole-home stench—especially during the hot and humid months.

Daily vacuuming can help absorb odors before they can become long-term problems. Baking soda and vinegar (NOT together) can also deodorize smelly carpets.

Cleaning spills immediately could reduce the odds of set-in bad smells.

4. Your Pets Made a Secret Mess 

cute small black cat

Pets and children are always the last to fess up when they make a mess in the home. So, your house may still smell after cleaning for several reasons if you’re a pet owner!

Unneutered male cats may “spray” on walls, doors, and vertical furniture. This instinct lets nearby female cats know they’re ready to mate, giving off bad odors that smell like ammonia.

Dogs may track in dirt, urine, or feces after spending time in the yard.

If that lingering odor smells like your pet’s food, wet dog or cat, cat litter, urine, or feces, begin investigating your pets’ favorite play areas and hiding spots.

A stinky litter box can be fixed with a fine layer of baking soda mixed in (or a complete litter replacement). On the other hand, an old urine stain will require a deep clean with an enzymatic cleaner to kill bacteria and the odor.

5. There’s a Dead Animal Somewhere in Your House

If it smells like something literally died in your house, there’s a small chance that something actually did.

Creatures like mice and raccoons can make themselves at home in your walls, ceilings, attic, vents, chimney, and crawlspaces. These rodents begin decomposing when they die, which releases a mixture of harmful gasses (like methane), bad odors, and other bacteria.

Small cracks within your home’s structure allow these smells to seep into your living quarters as they rot. Swarming flies and wet spots—caused by the body liquifying (eek)—are common indicators of a dead animal trapped in your house.

It’s best to call pest control to locate and get rid of the critter instead of searching for it yourself.

6. Your House’s Plumbing or HVAC Need Cleaning

bathroom sink p trap

No amount of surface cleaning, mopping, or air freshener spritzes will make a difference if the problem lies within your house’s bones. Fortunately, household odors caused by plumbing and HVAC issues are also among the easiest to detect.

For example, a hydrogen sulfide or sewer gas (or rotten egg) smell in a tub, shower, and sink drains could indicate blocked air vents or clogged drains. The fix could be as simple as pouring drain cleaner down the drain or cleaning out the P-trap under the bathroom or kitchen sink.

When the AC or heat kicks on, unpleasant odors may suggest air ducts that require cleaning. However, on a milder scale, the issue is sometimes easily. It could be as simple as vacuuming your home’s vents or changing your air filters if you haven’t done so in a while.

Always call a professional for more persistent or complex plumbing and HVAC issues.

7. Your House Has Hidden Mold or Mildew

mold growing on wall

If that lingering stench has a musty, stale, or damp tinge, the cause could be hidden mold or mildew growth somewhere in your house. So now, the question becomes: where is it?

Surprisingly, mold can grow just about anywhere. However, it seems to thrive best in 77–86 °F (25–30 °C) temperatures and high humidity above 55%. 

Naturally damp areas of the house are particularly problematic. Damp rooms with poor ventilation “trap” moisture and odors are more likely to double as breeding grounds for the fungi. That includes bathrooms, beneath carpets, tubs, showers, cabinets, under sinks, garages, and basements. 

Mold spores release a musty smell—in the form of microbial volatile organic compounds—as they grow.

If you suspect or mildew are what’s making the place smell bad, check these common problem areas first. Be sure to look for fuzzy, raised, or miscolored blotches and stains, all of which are signs of mold or mildew growth.

Call a professional to remove mold if it appears to be black mold or widescale.

8. Your Kitchen Appliances Have a Grimy Build-Up

kitchen oven

Be honest: when was the last time you cleaned your refrigerator, oven, garbage disposal, or dishwasher? Well, if it makes you feel any better, a survey from Cinch Home Services revealed that one in five people never clean their dishwashers.

Kitchen appliances are an easy-to-miss source of many relentless household odors and often the last place you sniff on the hunt for the stench:

  • A smelly dishwasher can be the result of drains or filters clogged with food particles.
  • Rotting food can clump up in a garbage disposal’s blades and pipes and lead to bad odors.
  • Dirty condenser coils, freon leaks, and old food can cause common fridge odors.
  • Grease and other residue could lead to oven-based odors.
  • Trash cans could also be the source of the smell, especially if you’ve thrown away rotting food.

Once you narrow down which kitchen appliance (if any) is causing your otherwise clean home’s odors, you can investigate the “why” and how to fix it. For example, an open box of baking soda in the refrigerator can be all it takes to neutralize stubborn fridge odors.

9. Old Foods or Beverages Are Rotting

We’re all guilty of shoving an empty pizza box under the couch or leaving a half-drunk cup of milk on the table, swearing to bring it into the kitchen later (… right?).

So, before you start ripping out your carpet or calling an electrician, check the following places for old food and beverages:

  • Under couches, beds, tables, bureaus, end tables, coffee tables, and nightstands
  • In between and under couch cushions and pillows
  • Tucked inside blankets, pillowcases, and sheets
  • In the microwave, oven, Crockpot, and other kitchen appliances
  • On tables, surfaces, or countertops
  • Behind opened doors and appliances
  • In the kitchen drain

This culprit is often the best-case scenario: once you find that half-eaten eggroll and toss it, the stench should dissipate shortly. However, that really depends on how long the food has been decaying at room temperature. Ants, roaches, flies, and mice also love foraging on leftovers.

10. Your Neighbor’s Apartment Smells Awful

Sometimes, your apartment reeks when it’s clean because your neighbor’s place isn’t.

Unfortunately, foul odors can enter your unit through:

  • Shared pipes
  • The HVAC system
  • Cracks or tiny openings in walls
  • Electrical outlets
  • Baseboards

How is that even possible?

Well, according to Zillow, a single particle of smoke is about 1/1000th the width of a single strand of human hair. That means tiny, microscopic cracks in window seals and pipes are just small enough for your neighbor’s scents to waft into your apartment.

That explains the faint smell of cigarette smoke in the bathroom and the smell of fish lingering by the front door. 

Of course, how you approach this problem depends on 1) whether you rent or own and 2) whether a member of a homeowner’s association (HOA).

If you lease, be sure to report the problem to your landlord or property manager. An air purifier with a HEPA filter and a bowl of vinegar can also help if you’d rather venture down the non-confrontational route.

11. Your Home Has a Gas Leak or Electrical Problems

opened electrical circuit box

If the previous ten reasons didn’t identify the source of the odor, the problem might be a lot more serious than you thought. 

If your house smells of rotten eggs—or is making a hissing sound—that could be a sign there’s a gas leak in your home. Natural gas is odorless until mercaptan is added to it, giving it its distinctive rotten eggs smell and alerting us to possible gas leaks.

Evacuate your home (along with all pets), open the windows, and call 9-1-1 or the gas company from outside your home. Don’t touch any lights, use your phone indoors, or use a lighter.

Sometimes, a fishy smell in the house stems from an overloaded circuit or other electrical problems, like frayed wires. Burning plastic or an electric smell could also mean an electrical fire somewhere in your home.

Call the professionals as soon as possible if you fear a natural gas leak or severe electrical problems.

Final Thoughts

If your house still smells after a thorough cleaning, try to track down the source of the stench. Travel room to room and, to quote Toucan Sam, “Follow your nose!” 

Don’t forget to open the refrigerator, dishwasher, washing machine, and other appliances during your search. Under furniture, behind the couch, and in cabinets, drains, and vents are common places for household odors to fester. 

Tip: Leave the house for a few hours (or days) if you’re becoming nose-blind to the odor. Or ask a friend to help you sniff out the stench with a fresh nose.