Why are black American bigots tolerated?

I don't think there are necessarily proportionally more black bigots than white bigots in America. Most are usually poor and lack education. Educated bigots are just more quiet about it. It is just that white bigots are put down for it. Is it because other whites are more aggressive to brand them? Or is it because normal middle-cl black Americans try to delineate themselves to the point they won't communicate with them? Do they have a right to expect racism to decline against them if they aren't willing to live up to the same values while treating others?