1. Guys who seem to think that the more you scream, the more weight you can lift. (Four plates a side on the leg press, psyche up for 5 mins, then slightly bend your knees, before jumping up and congratulating yourself)
2. The idiot newbie's who take all the plates off one end of the bar and then wonder why the bar flips off and lands on their training partner.
3. People who give incorrect advice out to people. (I was doing pressdowns and some guy tells me to keep my elbows in. I tell him "I've just done 3 sets with my elbows in, the last one is always with more weight and a bit of 'cheating'.)
4. People who use the machines wrong.
5. People who obviously can't be bothered to find out how to train correctly. (There was a guy the other day doing db kickbacks. But he was just hanging his arm down and swinging it back and forward. Even his mate, who was doing them right, didn;t bother telling him.)