If your house has a distinctive and offensive musty odor, understanding what's behind this condition can be critical to home care and maintenance. While the smell is unpleasant, it can mean a more serious problem with your home -- the presence of mold.
https://www.hunker.com/12000261/why-does-my-house-have-a-musty-odor
Eliminating Household Odors. The air inside your home can be two to 100 times more polluted than what's outside, according to the Environmental Protection Agency. And chemical air fresheners only add to the haze. For healthier ways to get rid of common odors, try these tips from green-cleaning expert Leslie Reichert. Pages.
https://www.thisoldhouse.com/ideas/safer-ways-to-eliminate-bad-household-smells
How To Remove and Cleanup Musty Smells. A musty smell in a home is a result of inadequate cleaning, poor or stagnant air circulation, high humidity and possible moisture problems. If you've ever noticed an odd smell coming from old furniture, clothing or books, or in a poorly ventilated area such as the attic or basement, you have a problem with mold, mildew or fungi.
http://www.housecleaningcentral.com/en/cleaning-tips/odor-removal/musty-smell-removal.html
Mold Smell Basics - What You Need to Know. 1  If you smell mold or mildew there's probably mold in the building. 2  Not all mold makes moldy smells. 3  Mold smells are not necessarily dangerous but they indicate a problem.  If there's mold in the building it should be found, removed, and its cause corrected.
https://inspectapedia.com/odor_diagnosis/Mold-Odor-Diagnosis-Cure.php
Musty Odors. Musty smells are associated with the presence of mold. There are many different types of mold, and they do have slightly different smells; however, smell is often a matter of personal perception. Examples of familiar musty smells might include forgotten damp laundry and wet basements.
https://www.hunker.com/12000261/why-does-my-house-have-a-musty-odor
Q. Help! My boyfriend's house is very smelly! We think it's from the basement. He has an open basement that does not have a door. Consequently, the musty smell of the basement comes all over the house, and everything -- clothes, furniture, etc., -- smell musty ... even outside of the home.
https://www.finishing.com/239/22.shtml
What's that smell? The musty odor on towels, tile, and basement walls can be a sign you have a mildew problem. Don't worry: With a few simple pantry items, you can completely eliminate the odor and stymy future mold growth. Here's how.
https://www.bobvila.com/articles/how-to-get-rid-of-mildew-smell/
So once you start smelling a musty, moldy odor, it’s time to take care of it. The poor air quality and odor problem won't stop on it's own and will only get worse. Molds and fungi are not healthy for your lungs. Mold spores and noxious gases they put off are aggravating to your health.
http://www.housecleaningcentral.com/en/cleaning-tips/odor-removal/musty-smell-removal.html
Here’s my dilemma. The house is clean, but there is a fusty, musty odor, like a large dog is secretly living in our house. We have an older, small house with the kitchen being basically open to everything. Sometimes I think it is cooking odors that are being trapped in the rest of the house.
http://www.home-ec101.com/musty-odor-in-a-home/
If you smell mold or mildew there's probably mold in the building. Most people correctly identify moldy or musty smells as mold. Some folks call these odors mildew-odor but since mildew grows only on living plants, it's more accurate to call these indoor odors and growths mold. Not all mold makes moldy smells.
https://inspectapedia.com/odor_diagnosis/Mold-Odor-Diagnosis-Cure.php
house has musty smell
A musty smell in a house is a result of inadequate cleaning, poor or stagnant air circulation, high humidity and possible moisture problems. An  inadequate cleaning, poor or stagnant air circulation, high humidity, and possible moisture problems results musty smell in a house.