It's really impossible to answer, as it's different depending on where you are. But I can tell you, that here in Germany being italian-looking generally isn't really your best bet to attract chicks.
I have another nice theory, though. Hope, that doesnt come off as racist in anyways, cause I'm not.
I think it goes further than just being about 'rarity' (though rarity is a big factor obviously).
If you want to score with girls who mosty listen to hiphop/go to hiphop clubs here in Germany, your best bet would be being black (especially african-american). Those girls are into the hiphop culture, where the alpha males are all black guys/african-americans (other than maybe Eminem). No wonder these chicks will usually like black men best. I doubt its much different in hiphop clubs in the US.
Girls in Japan see a lot of white men, the European looking guy in the movies/pop culture, etc.. No wonder japanese chicks are said to be so into caucasians (though probably at a hiphop club, girls might like black guys even better).
Say the next big trend wasn't hiphop/r&b, but the whole world obsessed over kung fu and it was considered as cool and as mainstream as the whole hiphop culture is, now. I would not be surprised if girls growing up with that trend would love asian guys!
Personally, I find myself attracted to a lot of different chick types from white to hispanic, to black and asian.
P.S.: I listen mostly to hiphop, etc. myself. I was just trying to assess the situation

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