Wow. I've never really seen this addressed. I have, through moving about, paddled with several different crews more than casually. And I've seen straight up blowouts (the worst I know of was with my crew on a Middle Fork of Salmon trip that I missed). I think that the clashes come from two directions, different personalities in a difficult situation and inexperience. All this combined can form the closest ties and the biggest fights.
Kayakers are usually different folks. Our sport is hard, dangerous, counter-intuitive, and sometimes flatout scary. The people who partake are an unusual sort. We all know that getting paddlers together is like herding cats--often kayakers all have their own idea of what is right. This sets up a stage for drama when you add the nature of hard water to the mix, the fact that the group must come together and act as a team to push on safely. An accident on the water forces the issue. I have paddling partners who clash occasionally, and it is mostly b/c of personality diffences. Placing two hard headed people in the pressure cooker of remote clV will eventually precipitate drama, if the 12 hr drive there didn't already. This issue us tough to solve.
On the other hand, there are kayakers who lack experience (or just a sense of safety). They cause alot of stife, as they don't get the team aspect, and can endanger others. We always endanger one another (any rescue I've been part of had inherent danger for all those involved), but we should consider all the risks when making decisions on a remote run, the Black Canyon being a perfect example. Inexperience can lead to poor decision making, not covering your buddy's ass, not knowing your place in the group, blowing critical eddies, etc. This has caused problems between myself and close friends. And I've been on both sides of the issue. This problem was any of us--it takes education.
Crews paddling hard water have to be very tight to work through these problems. It is surprising that so many good, tight crews exist. It helps when everyone is on the same level, as Livingston said of his crew. Livingston, cherish it, next year one of your buddies will have gotten married, another will be working too much, someone will move, and you will have an up-and-coming hotshot joining your group who can't throw a bag or never looks over his shoulder.
Good subject. Hopefully Curtis you can work it out with your pards. 95% of my experiences have been great, but I've butted a few heads. Along with everything else, kayakers tend to be really cool, great people. I'll bet that the "ass" you described would put his life on the line for you at a moments notice, given the need.