If laundry is left wet for too long, it can develop a musty, unpleasant smell often described as the "wet dishcloth" odor. This happens because damp fabrics at room temperature create the perfect environment for bacteria and fungi to grow. A 2012 Japanese study identified a specific bacterium called Moraxella osloensis as the main cause of this smell. The study found that this bacterium produces a compound responsible for the odor and can survive washing, thriving in wet laundry that isn't dried promptly. In addition to bacteria, fungi such as mold and mildew can also contribute to the smell of wet laundry. These fungi release volatile compounds, including geosmin, which gives off an "earthy" scent similar to that of rain-soaked soil. Human noses are extremely sensitive to geosmin, able to detect it at concentrations as low as a few hundred parts per trillion, making it a very noticeable component of the odor. The type of fabric used in clothing also affects how quickly it can develop an odor. Cotton is hydrophilic, meaning it absorbs water easily, which leaves fewer places for oily residues from sweat to build up. Polyester, on the other hand, is hydrophobic and lipophilic, meaning it repels water but absorbs oily compounds from sweat and skin oils. This makes polyester more likely to trap odors. A recent Canadian study found that polyester retains more odor-causing compounds than cotton or viscose, increasing the likelihood of developing a smell. To address smelly laundry, washing the items again at the highest temperature they can tolerate is recommended. Soaking the laundry in a concentrated solution of household vinegar before washing can help, as vinegar is a natural antimicrobial. Preventing the problem from starting is also key—moving laundry from the washer to the dryer or a clothesline within 30 to 60 minutes can stop bacteria and fungi from growing by removing the ideal conditions for their survival. Laundry boosters containing oxygen bleach and enzymes can enhance cleaning power and help break down biofilms in washing machines. Running a hot maintenance cycle and regularly cleaning the seals and drawers of the washing machine can also help prevent bacteria from re-establishing themselves. While hot water is effective in reducing bacteria, not all fabrics can handle high temperatures, so it's important to check garment labels for washing instructions. Balancing the need to wash clothes in cold water to extend their lifespan with the need for hot water to prevent odors is a key consideration from a sustainability perspective. If clothes continue to smell after washing, it might lead to premature disposal, highlighting the importance of proper laundry care.