I believe most of the abusive players I have encountered have been level 50-55. Almost never below 50, and I'm not a strong enough player to have much experience above level 55.
I really feel that a reporting tool would be a huge boon to the site - like somewhere where you can post a screenshot of someone cursing at you or using foul language or whatever. If there was a zero tolerance policy against this sort of abusive behavior, and a good way to report it, I believe the behavior would cease overnight. I would be very pleased to see something like this added as a feature to the board. It has been sorely needed for a long time. As it is, these players know that they can get away with this behavior and that there is no recourse, so they just continue doing it with no fear of anything happening.
I actually believe some of these people simply enjoy having a venue where they can be a total prick in safe anonymity, never having to take responsibility for their words as they are safely hidden behind their screen.
Thank you everyone for your responses. Stef, thanks for at least considering this. I think it would be worth your time and energy to make this happen.