I'm not sure why it would offer much advantage over cash.  Bitcoin is useful for the sale of illicit goods because it enables a remote transaction.  You don't have to meet the seller.  With prostitution, I'm pretty sure "meeting the seller" is the point.  I suppose it might be useful from a prostitute's perspective to reduce the risk that you're robbed by your client.  Prostitutes can always demand payment up front, but with cash it's possible that the client could try to steal the money back after the services have been rendered. (And unfortunately, prohibition always increases the risk of violence and theft because it makes it difficult or impossible for the victims to use the police or the courts to seek redress.)  With Bitcoin, the payment can be sent to an account that's stored offline in a remote location. That way it's impossible to return the money immediately even under duress.