Yep funny observations. The average guy in the gym today can't even curl a barbell properly...even with the aid of a preacher bench. Its bad enough when using one that they bring the bar up to 90 degres from teh floor, this forever damnign themselves to 15-16" arms dispite beingon a gram of test a week, but no, the guys have to lean back and brend the bar all the way past 90" and over their shoulders. Same with barbell curls. Don't they realize that if the bar goes higher than your nipple you are nto stimulating your bicep any more? Bench press and lat pull downs are pretty bad also. They are considered whole body workouts. Squats of course, if done at all, should not have a range of motion in excess of 4 inches.
Trains? Most of the trianers I see have nothing over a 12" arm, and if they do, they are fat and have a 40"+ waist. Shit, try getting yourself into shape before you start telling other people what to do.
BTW, I am all about the mirror. I like to observe my form, make sure its perfect,a nd watch the muscle work on each rep, and I practice posing after sets (Arnold always recomended this).