When people say "drab" or "asinine" or my anti-favorite "and it's not even close". Usually when one side of an argument is almost certainly correct that makes the topic in question a hard topic to debate for the opposition. That people usually manage to leads me to question the validity of the statement.
When people correct spelling or grammar and make similar mistakes without acknowledging they do the same thing.
Mod sucker-uppers, I'll name no names.
People who don't respect the hierarchy. Nobody got to the position they did by accident. Every mod and every high rated poster is so because it's generally acknowledged that when they post non-spam, no matter how often they opt to do it, they are highly capable and even have flashes of character or originality in their work. Some more than others.
How many people jump on someone when they do something wrong. Only takes one person to point out a mistake, but you'll always have another 25 to drag it on and add nothing new and constructive.