Just how long do you leave your laundry in the washer? A few minutes? A few hours? A few days? You're really not supposed to leave 'em in there for more than a couple hours at most...everything will grow sh!t if you leave wet organic material in a dark, damp location.
Futher, DO NOT USE REGULAR BLEACH ON COLORED ITEMS. Only use "color safe" bleach.
Gotta love ATOT...from girls to beer to washing machines, we answer it all.