Your argument is 5 hundred years of interbreeding? the Merchant of freaking Venice? Apart from the mass serial rape in the beginning, until recently, such crossovers would be rare, a boink sure, but marriage ratified by church and state? No one can prove what happened 500 years ago so it's a question of personal preference that a seeming Latino may chose to claim that he has a little Incan blood in him or her, but really with no obvious proof, isn't he or she just a little bit of poseur if they know there's no proof? Alternatively I'm assuming (yes I'm making an ass of you and me.) that most of the Latino's living in South America don't think of themselves as Indians, don't want to be Indians or even are not Indians. Besides, after the massrape that intertwined the races and pacified a few not so sturdy civilizations, Spain flat out spent 300 years sending still thousands upon thousands of more non-rapists to colonize as much of America as they could. So yes, it's pretty obvious because of history that most South American Indians have Latino or Caucasian blood in them, be it obvious or not, but the other way around as suggested above is not so endemic because racism used to keep everyone separated.