You will get rude people. If the situation escalates past a simple "Ma'am/Sir, I apologize for the situation but I am following policy. This policy exists BLABLAHBLAH..." you call a manager/coordinator.
Disney doesn't pay you enough to take getting yelled at by guests. Sometimes you will be. Sometimes you will have the nicest conversation on earth and sometimes you will think that a guest is legitimately the dumbest person on the planet... or that they are hellspawn. Regardless, give them a smile when it is appropriate, look upset when appropriate, and call a manager.
My managers probably think I'm an incompetent loser because I call so often, but in my last line of work, you passed problems along so they were no longer on your hands anymore, so it wasn't your responsibility. I like giving a problem to a manager who has authority to do things to make it better and defuse the situation.