Place a dishwasher-safe cup filled with plain white vinegar on the top rack of the dishwasher. Using the hottest water available, run the dishwasher through a cycle. The vinegar will help to wash away the loose, greasy grime, sanitizes, and helps remove the musty odor. Next, sprinkle a cupful of baking soda around the bottom of the tub and run it through a short cycle. The baking soda will help freshen and removing stains.
"Good old Martha taught us that rather than buying those ridiculously expensive anti-slip mats for a rug, just turn it over and run a few lines of acrylic-latex caulk every 6 inches or so. Let dry and flip over and your rug wont be going anywhere!"