It's a weird problem, but I have this feeling that it's probably a problem lots of people wrestle with, and don't say anything about because it's a weird, awkward, uncomfortable sort've thing.
Whenever I paint someone of another race--I'm a nondescript white chick--I worry that I am doing some horribly stereotypical carictature that will someday go down in history alongside "Song of the South" and the crows from Dumbo. And so in panic, I tone down any parts that might possibly be overexaggerated in any way, with the end result that they all look like a buncha white guys in tinted pancake makeup.
For example, right now, I have to do character illos for a sourcebook on the Yakuza. They're black and white, so I don't get to be saved by skin tone, and they gotta be Japanese guys, because--well--they're the Yakuza! And so I'm going through, ref in hand, carefully drawing the epicanthic eyelid folds and the somewhat narrow chins that half these guys glaring out of the Yakuza group shots seem to have, (and the glare, lord, the glare. Nobody can glare like a dozen Yakuza) to try and express that these are lean, mean Japanese guys, damnit, and then I stare at what I've done and go "Lord, I've drawn slanty eyes. I'm going to hell for drawing this, and someone's gonna accuse me of hate crimes as soon as it hits the shelf."
The last time this came up, I was trying to draw a black woman, and she wound up with lips approximately a micromillimeter in width because I got so damn neurotic about any possibility that I was playing into a racial stereotype.
The hell of it is, I'm delighted we don't all look alike. I used to work with this guy from Nigeria who had skin that spectacular so-black-it's-purple shade and I regret terribly that I never got a chance to paint him, because he was gorgeous. But at the same time, it's such a terribly charged issue that I find myself choking whenever I portray anything along these lines, even if my refs are insisting that this is TOO the way it should be. I am homogenizing out of guilt. And that can't be good.