A washing machine that smells requires a thorough cleaning. A bad odor may indicate a build-up of soap residue, grime stuck to gaskets around the door, or even mold or mildew growth.
Newer model washing machines have a built-in cleaning cycle that needs to run once a month to ensure the machine stays clean. If the machine does not have such a cycle, you can clean it by using liquid bleach or distilled white vinegar on a hot normal cycle with an empty load.
Always empty each load of clothes soon after the cycle completes so the moisture does not sit inside the machine for a long enough to produce a musty smell. Also, leave the lid open or ajar so the drum can properly air dry. Pet owners need to let the drum dry and then vacuum out the residual pet hair.
Running a load of clothes with white distilled vinegar in the bleach dispenser or a Downy ball on a regular basis helps stop the formation of soap scum and minerals as well as soften any current build-up. It also keeps the pipes and gaskets clean to prevent the growth of mold and mildew.
Many overlook the inlet house filter when cleaning, but a clogged filter can lead to a mineral or debris build-up producing a foul odor.