O my goodness I get this too! I was doing deadlifts the other day and I am sweating and trying to breathe. This guy walks behind me and says "why don't you smile?!" After my set I slammed the weight down and said "BECAUSE IM IN PAIN!" Do they not think that as women we can train intensely?! When I train I like to be focussed and intense. I'm not there to smile and look pretty. And those girls who do walk around smiling, with their hair down, and not sweating...are just there to get attention from the guys. GRR!