Personally, I haven't had much issue with etiquette. Most times I can fish are when others can't, so I rarely run into other people. When I do, they are usually nice. Only twice, in four years, have I had a guy come to the same spot on the river, chat a bit and then ask if he can jump in beside. I always accept and end up fishing with them. As of yet, I haven't had any issues with drift boats either. The guys that I have seen have always seen me from far enough away to make a wide berth. I have even heard the guide (or the guy on the oars anyway) tell the guys fishing to cast out the other side as they drift past. Usually have a friendly chat and let them know what's working, etc.
However, with all that's been said here, and in many other threads, that will one day change. I just hope I'm in a forgiving mood when it does. I'm not usually one to conflict with someone though, so I would be an easy target for guys wanting to poach my water.......