I have had black friends point out incidents of anti-Black racism to me that I definitely hadn't seen before, but I have as often had black friends perceive racism where definitely none existed, and black friends who did not see it where it definitely did. It happens enough, that I think only people who don't have much interaction with different races and classes would believe that only black people can tell what racism is. People have all degrees of sensitivity, empathy, perceptivity and hair-trigger paranoia; sometimes in the same person.