I'm calling possible BS on this one. I'm sure there are people who'd do this (regardless of the race of the borrower), but someone across town will give you the best deal your credit will qualify you for. I'm sure there are cases where this happened to blacks, but till I see some real statistics, I'm not convinced this was done to minorities any more than it was done to whites, given equal credit histories.
A lot of those mortgage companies were actually run by blacks. I sold my house to a (nice) black family and they used a minority mortgage company that didn’t know its a-hole from breakfast and caused a major delay in the closing. That p*ssed me off, but the buyer had it worse - he was running around with his furniture in a truck for days because of it. I ended up letting him put it in the garage before the sale closed.