Sometimes the problem is you. (Sometimes, it's even me. I know you're shocked.)
If you've been playing WoW for a while, one fact is indisputable. You learned how to play your class or role by playing. It is in groups that we learn our toolkits, how to perform our role properly, and each dungeon or raid we run not only teaches us how to run that dungeon or raid but gives us the context we need to tackle new content down the road. We learn by doing, and moreover, we learn by interacting with our groups, be they guild runs or pickup groups. PUGs can be hard schools, but they're invaluable in jogging you out of your comfort zone and getting you to think about what you do and why.
If you think of your instance runs as where you go to farm a quick batch of justice or valor points, you're part of the problem.
You are there to learn and even to teach.
You are there to work together with four other people you may or may not even know. You are there to share knowledge, to help the group succeed, to learn skills you'll need later, and to help other people learn them. While some people will always have better reflexes than others, the general difficulty of even current heroics is not so great that a group cannot succeed even doing things with a brute force approach, trying to smash down every pull. What group coordination and information sharing can accomplish is to make it all much easier, take less mana on the part of your healer, and train everyone (including you, no matter who you are and what your role is) to do things more efficiently and with less downtime.
Part of the problem
Modern heroics are designed to effectively cause a good group to reeducate its members. When game design changes, it's the players, not the designers, who do the work of teaching each other what to do. If you're not willing to learn (no matter how awesome you think you are) and not willing to teach, then you're not helping the group succeed. That's what it all comes down to.
If you think you're too good to do either one of these things, then don't queue. You're not helping. It doesn't matter how well geared you are, how long you've been playing, or how awesome your numbers are, if you decide to be a drag on the group by not listening to what others share with you or not sharing what you yourself know. If you're going to get impatient, slag everyone off and leave the group in a huff, you just wasted everyone's time, including your own.
Right now, we're all learning. We're all teaching. If you can do either of these, you can get through a PUG. It's that simple.
World of Warcraft: Cataclysm has destroyed Azeroth as we know it; nothing is the same! In WoW Insider's Guide to Cataclysm, you can find out everything you need to know about WoW's third expansion, from leveling up a new goblin or worgen to breaking news and strategies on endgame play.