There isn't any question that he knows his HD. In fact, he's one of the most knowledgeable people playing the game. It's the "I'm right, you're wrong and I refuse to concede an inch" attitude that irritates me the most.
Oh, and the constant habit of stating opinion as fact.
And who could ever forget the whole "jewed 'em down" fiasco. Got banned for that, then after the offensive comment was removed, created an obvious alias (gonarayshell) and tried to deny posting the comment in the first place, even though literally dozens of people had seen it. Took him forever to apologize and I'm still not sure he thinks what he said was wrong. Sad, really.........