Lube and the Vagina

Okay so I know that most people (me) don't give much thought into what chemicals are in the makeup they wear and food they eat, so like they will just use things. But I have always wondered what the effects of flavored lube, or lube in general, are on the Vagina. Like can you get a UTI? Is having sweet stuff in there such a good idea? And how in the world do you clean it out(Besides a douche)? Are you even supposed to clean it out?