The reason I don't like hecklers at local shows is that usually there is no pretense with some bands; they're just trying to play live. They know they may fuck up and they know they're not perfect. Plus, everyone has an off day, playing-wise. Some shows you'll play like a god and some you won't be able to do anything right. There's no need for rudeness unless the band truly deserves it by being pretentious asses.
I've also noticed that very rarely do serious musicians or musicians with any modicum of ability ever heckle; they know what it's like to fuck up on stage and they know it's not a nice feeling.