I believe there are people who genuinely care about what happens to black people as a whole, who believe they not only have had a bad deal historically, but that it persists and still needs attention. I believe there are people who care about the rights of women, of Hispanics, of the disabled, of Native Americans, or many other categories of people, some of which they themselves do not belong to but have concern for. That's Sheep's Clothing.
Sheep, of course, have sheep's clothing naturally. They don't have to knit themselves an outfit.
There are others whose complaints are at root entirely personal. They are wired to feel persecuted - it can be quite delicious if there isn't any real cost - and take whatever cause is at hand to explain their oppression. I had a patient who was active in libertarian, Native American, Wiccan, and feminist causes. Well, no she wasn't active, really, not in any sense of showing up at meetings, licking envelopes for mailings, giving money or anything like that. She was active in declaring how persecuted she was, for all these reasons. Not for her general narcissism and rudeness. She was more of a wolf, looking for whatever sheep's clothing came her way to wrap herself in. She was into wolves, too, BTW, with T-shirts and complaining about how they were misunderstood animals.
How does one tell them apart? It is reasonable to at least attempt discussion with the former, however much we fear that we may not find much common ground. Yet we all sense that it is pointless to engage in discussion with the latter, at least on political and cultural matters. (They may be hurting puppies who can be approached on level of empathy that cuts through all the causes and ignores them, but that's a different category.)
I can tell you one way right off the bat. Those who cannot acknowledge that the plight of their group is better than it was in 1925 or 1950 or 1975, or who cannot abide to remain in that discussion even if they briefly acknowledge it, are working from personal issues, not larger ones. You cannot count on them to actually care about African-Americans or assault victims or immigrants. It's all a pose. Their causes are only weapons used in the service of getting their own bottomless needs met.
I object that legitimate advocates find it convenient to let the wolves run rather than fence them out.