Was watching a UK docu called "Bring Back Star Trek" when I heard the ugly remarks.
Whitney struck me as a VERY bitter person. Watch the interview for yourself and see if you can detect any bitterness, envy, and/or racist tones. I sure as hell did.
(So bitter, in fact, that she outright SAID to the interviewer that the show "Ruined her life", and she hit the bottle, hard, for many years after.)
Oh - And along with the 'black' remark, she also called Nichelle's part on the show a 'glorified extra'.