Don't laugh: Even your dishwasher needs a good cleaning periodically. Soap residue, food scraps, and build up can dirty your appliance over time, eventually compromising its efficiency. You can restore its cleaning power by giving it a wash—but you don’t need to make a big deal out of it. Place a dishwasher safe cup of vinegar on the top rack and run it through on the hottest water setting. When you return, your dishwasher will be squeaky clean.