You know the moment: you take off your shoes after a long day, and the smell seems to hit you before you even have time to sit down. You check your socks, sniff the shoes, and wonder, how did they get this bad? Why do shoes seem to hold on to odors even after they have been sitting untouched? Don’t worry. Smelly shoes are a common problem, and there are several simple ways to deal with the odor. You can start by letting your shoes air out, but when that isn’t enough, it may be time to reach for two simple household staples: baking soda and white vinegar.