a) if they are white, calling black people "lazy niggers" and saying they're all on welfare, though President Obama doesn't appear to be, but none of them like to entertain the fact that they are being presided over by someone who - gasp! - has darker skin then they do.
b) if they are black claiming total innocence on the racist front, and responding to a remark that is racist against black people with a remark equally racist against white people
c) judging from skin color, even subconsciously, and generalizing all white people into racist assholes, even if all they did was not meet your eye in a crowded mall or whatever.
racist black person: shut up you racist crackerhonky!
neutral mixed person: uh, that was racist too, moron.
RBP: its payback for all the racist B.S. my grandma had to go through, pickin' cotton and all -
RWP: yeah, you should still be picking cotton, porch monkey!
RBP: - SHUT UP REDNECK!
Michael Jackson: Sha'mone, you guys, it doesn't matter if you're black or white! *grabs crotch*
*RWP, RBP, NMP, and MJ all start dancing Thriller, proving people of all races can still dance together in peace, without using a racial slur! yay us!*