I had an old barber once with a similar policy, only he didn't have a sign. But one day I am in the chair getting my hair cut when a young black guy comes in and sits down. Without even missing a beat the barber says:
"Sorry son, I don't cut black hair, unless you got Cab Calloway hair."
I busted out laughing, the guy sat their stunned (perhaps unaware of who Cab Calloway was) then slowly got up and left.
I don't think the barber was a racist, he just needed to work on his tact.
Who is Cab Calloway?