Originally Posted by DC2

Don't rerack the weights
-No really, it's very appreciative of you to leave your weights on the bars so the next guy can put forth the extra effort of cleaning up your shit!

Never bring a towel
-Nothing feels better than sitting down and soaking yourself in the previous guys' sweat. It promotes the goodwill among your bodybuilding comrades working towards a common goal. It's really okay for me to immense myself in your bacteria!

Socialize next to the machines
-This is good for networking. Not only it blocks other people from having them work on the machine, it forces them to go try new machines! No really, it's okay I paid $40/month for you guys to hang around and look good talking amongst your buddies on machines you're not even using. I'm going to assume you guys are discussing ways to get even bigger!