People are inherently prejudiced toward or against every superficial trait you can find on someone, that doesn't mean putting stock in them is desirable or that the playing field is in any way level. Saying "well we're all a little racist" is just a personal convenience to excuse whatever you feel like.
Everyone's a little bit bisexual too, but that doesn't mean every supposed heterosexual will feel attracted to the same sex in their life. Do they deserve to be called liars just because the theoretical possibility of that exists?