If you are feeding your dog dry kibble then you may get away by wiping it once a day but if you feed them wet food, then you must clean the bowl after every meal. It's also a good idea to sterilize the food bowl by running it through the dishwasher on high heat once every week. Phys.org quotes "The dog water bowl has previously been identified as the third most contaminated item within the household, which suggests that they are capable of disease transmission." So it is very important to clean the dog food bowl on a regular basis.