Oh, God, yes! I get that all the time. Mostly in the Tolkien fandom, but in the others, too. Especially annoying is the fact that most of the time they are talking rubbish, because I do my homework and am rarely wrong where canon is considered - even Tolkien canon, which isn't an easy thing to manage - and then they post their "corrections" in review boards like TFF, where I can't answer, and it remains for everyone to read that I apparently don't know my canon. Grrrrr!

The other thing I "love" is when they tell me that this or that character would never act the way I had them act. How the f*ck do they know? Just b/c untalented screenwriters can't write any good character development, it doesn't mean the rest of us can't, either!