When you open your dishwasher, you expect to see either clean dishes that are ready to put away or dirty dishes that need to be washed. You don't expect to see black slime or encounter a foul smell, but both could be lurking inside your dishwasher.
Slime and Smell
Black slime and a bad smell coming from your dishwasher are problems that get worse as time passes. You'll notice the smell first: a pungent, musty odor that rolls out of your dishwasher every time you open the door. The smell might fade immediately after you run a load of dishes, but it will soon return. The black slime builds up inside the unit, usually around the door's rubber seal. It can also appear at the bottom of the dishwasher.
The root cause of the slime and smell inside the dishwasher is food debris inside the unit. It can build up, especially around the rubber seal and at the bottom of the dishwasher. The food particles attract mold and bacteria, which combine to make the bad smell. The combination of decomposing food and slick mold can look like black slime, although in some cases the color is closer to dark green or brown. Water helps to wash away some mold and bacteria when you run the dishwasher, but they build back up.
Clean up the food debris and wash away the slime. That will get rid of the smell in your dishwasher, too. Soak a thick sponge in white vinegar and wipe down the interior of the unit, paying special attention to the seal and the bottom level of the dishwasher. The thick sponge will protect your hands from broken glass or porcelain in the bottom of the unit, but take care when cleaning in that area. Rinse the sponge often and keep it wet with vinegar, which kills mold and deodorizes the dishwasher. After all visible mold and slime are gone, fill a cup with white vinegar and place it in the top rack of the dishwasher. Run the hottest cycle possible. The combination of hot water and vinegar will remove any lingering odors in the unit.
Prevent the slime and smell from returning by scraping and rinsing dishes before placing them in the dishwasher. This cuts down on the amount of food the unit needs to rinse away. Avoid jamming too many dishes in for each load. Taking these steps will help your dishwasher fully remove and dispose of all food debris in each load. You can freshen your dishwasher by running an empty load except for 1 cup full of vinegar.