This article on affirmative action in Brazil is interesting. Here is the conclusion:

"I don't think there's any doubt that some middle-class white kids are taking advantage of the system by declaring themselves black," said Salgueiro, the admissions director. "It's disappointing because that means the program is not always benefiting poor or underprivileged kids. But at the same time, what can you do? We have no idea really who is black and who is not. This is Brazil."

Bulbul, the black filmmaker, acknowledges that the quotas are an imperfect tool, and that the solution really is to expand education opportunities to accommodate people like Fracescutti and poorer Brazilians, both black and white.

Brazil seems the classic case study in how cultural norms influence how genes assort themselves in a mixed population. Since most of the population is part black by ancestrty they are looking for phenotype, so if they want to get practical and cut out cheaters they need a system of auditors like the old South Africa had to verify racial identity. Perhaps this system will impose a high enough cost on "whiteness" that "good features" will be redefined in Brazilian society.