If you can tell me where Colin Powell stands on healthcare issues, poverty issues, tax issues, environmental issues, education issues, etc. -- and then say "I agree with most of these stances, and that's why I'd vote for him" -- then I'd say you've still got some credibility left.
If you can't tell me where Powell is, though, on all this stuff...well...then that tells me that you would just vote for him because (a) he's a Republican and you're a knee-jerk voter for Republicans; (b) he's Black, and you're eager to "prove" you're not racist by claiming you'd vote for a Black man; or (c) he's both a Republican and he's Black, and you're a knee-jerk voter for Republicans who would love to be able to say that he voted for a Black man.
The poet e.e.cummings (himself a bit of a bigot, particularly toward Jews) once said, "To like a fellow just because he's black is just as bad as to not like him because he isn't white."
Translation: Voting for Powell because he's black is just as bad (i.e. just as racist) as to not vote for him because he's black.