Smelly.......?

What cause washer to smell like wet stinky meldew clothes inside of the tub? None of my clothes smell anything like that. I don't leave my clothes in washer when it done washing. How do I take care of this? It's gagging every time I open the lid to add bleach to the wash or take them out. It's really bad. My brother's feet smell good compare to that and his feet are OH WOhooo bad. I thought maybe it could be the lints in the washer? If that the case? How do I deal with this problem? Thank you.