For the most part, you can easily clean up most food stains inside your cooler with dish soap and warm water, especially when you first come back from your trips. However, if you’ve left your cooler unchecked and uncleaned for a long time, and you find it having uninviting odors or tough stains, you should fill the inside with a solution of water and bleach. Leave it for a couple of hours, then come back and finish the cleaning with soap. Nonetheless, the plastic materials will allow for simple cleaning in most cases.