Disagreeable people can be good. People who dislike you (and thus stare at you with death glares) are not necessarily evil. So, no, I'd say that it can't be determined just by looking. >>>>
Okies, defending my idea futher, here is another argument. Trying to bring the concept into the game, being evil guy, looking like evil guy (dark skinned, dark clothed, surrounded by black auras or whatever) he still can smile nicely, looking at you with his glowing red eyes, he still can persuade, like that snake persuaded Eva in Eden
The question is, how deeply developers will want to bring this concept into life?
How people will react to different outfits?
How outfits will depend, and in what way, on different actions and general allingment?