I can't find any information about guinea pigs not liking water. Maybe they are not used to being in water. You can try simple "sponge baths" with warm wet towels. Personally, I would avoid giving them a bath. It is a two person job. But do try to avoid water in the ears. read more
You should at least clean your cage once a week. Some guinea pig owners like to spot clean daily and do a full clean every 2-3 days due to the amount of mess guinea pigs make. Clean the bedding, fleece, water/food dishes and any soiled patches. read more