Lifting Form, are there any major no/no's??

[CobraUTAH]

My question is are there any form techniques that you have seen or heard about that are truly bad for you or that are just a waste? When doing dumbbell incline press, I used to only drop the dumbbells until my arms made a 90 degree bend at the elbows and then went back up. Since I've started my new 5x5 routine I'm making a point of going all the way down and getting a fuller rep. Is there much difference between going that deep and not. Same with Dips when are you going to deep. Mainly I notice that now the deep stretch I get from the incline dumbbells make my chest hurt right at the insertion of the shoulder, I'm guessing it's just a major stretch that is caused from the deep reps. Another question although I don't do this is lat pulldowns or shoulder presses behind the neck I've always heard it's a major no-no, but is that true?

 

[Thaibox]

When you start shoulder pressing serious weight, going behind the neck is definately a liability. As for pulldowns, you can only really squeeze your blades together and get full contraction when your back is arched(head up).

 

[Nonerz]

Another question although I don't do this is lat pulldowns or shoulder presses behind the neck I've always heard it's a major no-no, but is that true?

seems that you'd be throwing your alignment out of whack! Very unnatural, not to mention uncomfortable. I think there are better ways to work your lats than that...just my 2 cents.