I don't mean to suggest that you would point someone out as a poolhopper

I just mean that if I am staying at the Poly and cannot find a single chair then I would ask a lifeguard for help in finding a chair - I'd be hesitant to move towels from a chair but hopefully they wouldn't! Actually, I would move a towel in a heartbeat. But people have started leaving magazines and sunblock too as "props" to make you think they're really around when they aren't. IT'S TRICKY, I'm telling you. It's a big problem and it's not just at Disney World! If you were to voice your concern about not being able to find a chair then hopefully that would jump-start a "crackdown", even if that meant a security guard going chair to chair asking to see Poly room keys. It was just an idea for one way to deal with it if it becomes a problem during your stay...
Tess -This was the first trip where I felt that I was certain of multiple pool-hoppers. I posted something about it last week when we ret'd but was hesitant to b/c I do not know other people's situation and in general I
try not concern myself with it.
This trip, a very nice man came up to me and offered me his lounge chair when he saw me standing on the beach looking for one... Later at the pool bar I saw him and told him again how much I'd appreciated it and he told me he was just there for the day and waiting for a friend who had never showed up??
A group sitting next to us on the beach was some teenagers who kindly offered to take a photo of my SIL and me. They were really sweet. When they were leaving the beach, I noticed that they (all 4 of them) had mugs from another WDW resort. Things like that lead me to believe that non-guests definitely make use of the Poly's pools.
Also, at AKL a year or so ago, I know for a fact this woman I was chatting w/ was not a guest of the resort b/c she told me herself that she wasn't

At Hard Rock Hotel about 6 years ago, a man with his young son told me all about Orlando and that HRH had the best pool and that he visited often and that the resort let him come just for the day