Why does my laundry smell bad?

According to Corina Wilson writing on the Mrs. Clean website, odorous laundry is often caused by mildew build-up in the washing machine. Damp laundry can also emit a musty odor if it is left in the washing machine or laundry basket for an extended period of time.

Mildew can be removed from a washing machine by pouring 1 cup of bleach or 1 cup of dishwasher detergent into the machine and running it for a full cycle. Odors can be removed from laundry by machine washing the garments in hot water with 1 cup of vinegar and 1 cup of baking soda. Adding 1 cup of ammonia or pine cleaner to the machine's rinse cycle also helps to eliminate strong odors from fabrics.