I have long had a bit of a problem with RPG rules and gaming advice that require the gamemaster to act as sole judge of good roleplaying and other appropriate play, either to award experience bonuses and other benefits for good play, or to teach lessons and good habits to the feckless and childish players. It has seldom seemed to me that being the gamemaster for the time being gave me a keener understanding and better taste than I had at the times when I was playing a character. And it has almost never seemed to me that any gamemaster in whose game I have played understood how I was playing my character better than I did.
But then, I hardly hold with experience points and other mechanical incentives for good play anyway. It seems to me that the only proper definition of and reward for playing well is that it should be enjoyable.