References are anonymous to all but the person you gave it to, everyone else see just the reference. It's only fair that way I think because it's only right he would have the opportunity to question why he received the negative. I don't know if it would be fair for clients to give escorts a bad reference as I feel that would be open to abuse.
I also think it would be a bad idea giving a bad ref for nuisance Pm's, that's what the block user function is for.