It really all comes down to what actions you (in the singular) can perform yourself at a show. Firstly, I will not (and have not) treated anyone differently at a show based on how they look (skin, hair, short, tall, wook, business-like, etc.) Nothing, certainly nothing so stupid as skin color, could matter here, because you're all degenerates to me.
Secondly, if I did see any kind of argument or fight breaking out based on if a person or group was being singled out and abused, or made to feel bad because of their race or ethnic group or other characteristic, or a female fan made to feel uncomfortable by some guy's actions, I really would intervene and make it known that is not OK here, and me and everyone behind me is not going to let anything shitty go down. No one should be forced to take that and we all should stand up and make sure it's not accepted. Now, I have not seen that personally myself, but I certainly believe people if they say it happened. No, what I see are the stupid assholes fighting about drinks or space or talking loudly or their own personal shit they should have left in the parking lot, and fuck them, they can go to the back of the lawn and fuck each other up, just don't ruin my time.
What we can do, and what we should do, is what we as individuals can do, and that makes the group better through our actions. Those are real, important things, much better time spent that reading this whole goddamn blog post, ain't no one got time for that shit.