Why are Malaysians so blind to see dirty politics done by Barisan Nasional (BN)?

They see it. But this society has gotten too comfortable with corruption, oppression and lawlessness that it becomes numb to it. Now Malaysian politics is all about fear, it's no longer about voting for who's better but against whom you fear. Simpletons who judge Anwar based on the media's lies choose BN, those who fear change vote for BN, the Christians are afraid of PAS and hence vote for whatever alternative available, the urban Chinese vote for anything that isn't BN, the Malays who fear their excessive privilege would be reduced vote for those who protect the Malay racists and so on. Only those who are better informed and see the long-term consequences vote intelligently.