The worst by far are "I have extra cash, what gun should I buy?" threads... I mean, not the "help me decide between these two", but a general "I want a gun, tell me what I should buy?"
Those are just moronic... Look if you don't have the presence of mind to figure out what gun you like, either wire me the money (because I sure as hell have a long, numbered list of what I want), or go ahead and donate it to the NRA.