It may have been a long time since you washed your dishwasher. And while it seems like his dishwasher should wash, the truth is that even appliances designed to make our best dishes shine need to be washed every now and then. Over time, food scraps, dirt, and soap scum build up in the dishwasher, which can not only leave an unpleasant odor but can also make your appliance run less efficiently. No one loves going to a clean dishwasher to find plates and bowls covered in film or detergent residue.