EDIT: I just realized how much of a whine this is. Flame me all you want!
A few days ago at the gym I was doing some DB incline presses and this dude was looking at me strange, the way you know he's going to tell you something is wrong about your lift. Sure enough, when I finished he said, "that's not the way you do shoulder presses, man." Wtf? Shoulder presses?
You might be surprised (or not) but this kind of thing happens to me at least once every day. I wish I was exaggerating. Granted, sometimes people are right. But most of the time they aren't, or are just pointing out a 'mistake' that only happened on my last rep because of fatigue.
To give another example, just yesterday a guy saw me doing chest flies on a cable machine, and he exclaimed, "You've got more weight on one side than the other! That's completely wrong!"
I pointed out that the machine has a simple pulley mechanism that's designed specifically to make the load even on both sides. A simple knowledge of elementary-school mechanics, it seems, is lacking in the general population.
Is it possibly because of the way I look, or walk, or talk, or whatever?
Sorry, I just had to get this rant out of my system.