We have neighbors that just got back two days ago. The answer for this question truly depends on #1 when you go (busy season, they don't want to allow it- slow season, it's allowed) #2 WHO you ask at the resorts and #3 How many people are in your party.
My neighbors asked the question last week at Royal Pacific and the answer was "it's not only allowed, we encourage it!" The other resorts are happy to have you because it may result in "spending money there as well as your current resort".
They asked on multiple occasions and got the same answer..."yes, it's allowed" BUT, twice, they received the answer "YES, as long as..." They said as long as it's not a busy season, or if your group is large."
They did receive a no one time, then the lifeguard that said no came over to them a few minutes later and corrected himself. He said "it wasn't allowed over holidays" but only allowed in slower seasons. He also said some will say no, because they don't really "know" and it's just the safe answer to give.
Our neighbors pool hopped, checked out towels from all locations and used room key to charge at all three "top Loews resorts". They did get 1 bar tender at Hard Rock that questioned if it was allowed, but he didn't make a deal out of it.
We are going to try it when we're there. We'll update when we get back.