Re: Pompous Baffoons
Just to kind of sum up my own thoughts...
One issue is relative rank, etc. There have been times I've been in someone else's class where I'm working with a beginner. As a fellow instructor if there is something I'm *really* sure he's doing wrong I'll do what I can. If the student doesn't listen/get it/whatever, I try to get the instructor's attention -- it is their class therefore up to them to deal with someone who isn't working off the same page.
If the person is nearer in rank (or higher), I might ask the instructor for help to clarify what I'm doing. Otherwise I just go along with it. Again, if I'm not the one teaching I'm not going to be stepping on the instructor's toes.
I do think, however, that the instructor should know this is going on. I've seen guys totally ignore the instructions of the sensei. Then noticed that the sensei stops correcting them. That seems to me to be an insidious problem since the guy doing it wrong probably thinks they're getting tacit approval when in fact the sensei has written them off.
So... Ultimately the responsibility is with the instructor. You can call the instructor over for "advice" in a polite manner to call attention to it. Then the ball is in their court. Hopefully they do something about it before it gets ugly, but sometimes things just have to get ugly.
If you're not a fellow instructor there's not much you can do except ask for clarification from your sensei. At that point I'd go back to avoiding the person whenever possible. Sometimes there are just people you shouldn't train with. Lord knows there are a few people I feel that way about myself.