I've been in SL for over 12 years and I've met a fair share of rude, obnoxious people, but I believe they are such a small percentage of the population, and they aren't worth the energy it takes to worry about them. If you find you are meeting an extreme number of rude people, perhaps you're spending time with the wrong type of people and/or the wrong places. It sounds funny, but I've found that different areas of SL attract different types of people, and while there is always going to be a sour grape/rotten apple in the bunch, some areas seem to have more than others.
Of course, there's always the possibility that it isn't the other people at all