Perfect Form and Maxes
I've talked about this quite a bit and have asked a lot of different people the same question; if you're doing a rep max, whether it be for 10 reps or 1 rep, things might end up getting a little ugly. Now this doesn't give you license to lift with poor form or to forget about some simple technique cues that are essential, but please don't think that things are going to be picture-perfect throughout the set.
For example, if you're going for a true 5RM, there's a good chance your fifth rep is going to be a little rough and might not be perfect. That's what it takes to dig down and muscle some weights up.
Now I can already hear the histrionic wailings of the Weak Point Brigade that will challenge me on this point, so let me be clear: I think good form is a great idea. But these are the same people who will tell you to arch your lower back when you deadlift, which is great advice when you're showing your 60-something year-old mom how to pick up a potted plant; the reality is that no one that pulls big weights with a conventional stance has a perfect low back arch. So I'm not sure what they're selling you, but I can assure you that you if you left it out in the sun for a few hours you could fertilize the lawn with it.
I just see too many people that ask me (and many others on forums) to evaluate their form during a rep max. There's a time and place for everything, and during a rep max of any kind is not it.
The problem with this kind of technique micromanagement is that people wind up getting too scared to go up against a big weight for fear that their form might not be textbook perfect and then, when they come up on their toes a bit or their head dips down, the Weak Point Brigade emerges and starts evaluating, nit picking, and worst of all, offering advice.
So in conclusion, lift like Conan: lift for Crom. Crush your limitations, see them driven before you, and hear the lamentation of the Weak Point Brigade!