There is also a (smaller but still existing) issue with anarchists showing up at peaceful rallies and protests in Los Angeles area. I have a friend that works security there and regularly sees idiots that have nothing to do with the protest trying to get black marks against any nonviolent groups. Its a common theme with anarchists to spread their crap around and try to make things worse for everyone else.

I'm guessing there are more in Oakland/bay area due to greater concentration of peaceful protestors? Sorta the anti-hippies.