All of the resorts now have a sign stating that the pools are guests staying at that resort only. It was also in the guide you get on check in.
For example, the WL guide listed the FW pool as being ONLY for FW guests, and vice versa. Do they check everyone's ID? Not always. Is the policy against pool hopping clearly stated? Yes. Is it OK to do it? I think it's wrong, but that's my own personal morality. Lord knows people do far worse. Let YOUR conscience be your guide. :animwink: