Well, you've picked a VERY hot topic - don't be offended by some of the posts that will likely be coming your way.
Disney's official policy is that only registered resort guests are allowed to swim at any resort pool - that mean you can't go to a resort and swim at their pool.
Some people do try to do this, however. Sometimes they succeed, sometimes they fail. The resorts with the nicer pools either have fences around them (and CMs that check to make sur you're staying at the resort) or are in the process of BUILDING fences to help control this problem.
How would you feel if you were turned away from a pool becuase you weren't a hotel guest - more importantly, how would you children feel? I my opinion, it's not worth the agony of trying to explain to the kids why they can't go swimming in that fabulous pool.
So, sorry, you can't pool hop.