Raccoons do often put their food into water, but they frequently eat it without any water too. They have plenty of saliva, and don't seem to be worried about dirt, as they will eat dirty food without water. Other sources say that they only dunk their food in captivity, but this has been observed in the wild, and the word "raccoon" comes from their Native American name, "ahrah-koon-em", which means "one who rubs, scrubs and scratches with its hands." I doubt that they were keeping raccoons as pets. At this point, the answer is one of my favorites in science. We don't know! Another mystery to be solved.