People can certainly be racist without admitting it, but I don't believe a handful of controversial umpiring decisions or even a bias against a particular side are any sort of evidence of racism. There has to be a reason to believe that the bias is racial in nature, other than the race of the players in question.
Basically, there are two assumptions people are making when talking about Hair. One, that he is biased against particular teams, which I don't really buy, but obviously it's a fairly popular argument among the fans of particular teams. Two, that he is biased against those teams because he is racist and wishes to persecute either the people of the nations those teams represent or the racial group that most of the players fall into. That has no evidence at all, it's just an assumption based on his conduct as an umpire, and an utterly ridiculous one IMO.
Hell, it may be that Hair is racist, I don't know the guy, but you certainly can't just assume he is because he is harsh on some players from the subcontinent. Same goes for Bucknor, Chris Broad and everyone else.