But wouldn't this be a reasonable feature used by the classifier to reach its conclusion? They can't control for everything, it would become meaningless. I thi

But wouldn't this be a reasonable feature used by the classifier to reach its conclusion? They can't control for everything, it would become meaningless. I think the questions about age/sex/ethnicity are sensible in that it's a valid question to ask whether it's just doing the naive/obvious thing or something more. But if you keep on removing the less obvious things then of course you'll reach a point where it's no better than a coin flip because it's basically comparing blank pictures.