How do minority voters discriminate between candidates that sort of "look like" them?

This is a serious question.
I can’t stop you from indulging in your normal reflexive and condescending Fluther doctrinaire moral judgement, but it would be interesting to get an honest point of view.

Black folks adore the President. They are ambivalent at best or disdainful of, at worst, of another black man, Dr. Ben Carson. Both men are well educated and well spoken and at the end of the day both are probably decent fellows.

Women love Hillary Clinton. They seem to have no interest in Carly Fiorina. One woman is famous because she is married to a former president and many people imagine this makes her special. The other woman was a successful business person and CEO of HP, and many people imagine this makes her special.

So, what is it? What is the “thing” that makes one popular among their like perceived minorities, and the other one not so appealing to the same constituency?