Agreed regarding back to back, although it has to be managed properly.
A professional like a lawyer or a doctor will effectively be booked back to back, but with enough transition time to get between meetings, and with the expectation that he/she will be properly prepared and presentable.
I don't care who the WG has been seeing before me, but she should leave at least 15 mins between bookings so that she doesn't smell of someone else's cum! We can't check whether she takes a shower or no, but if a WG doesn't smell fresh then during an initimate interaction with the client (kissing, DATY, being close to her skin) that's unreasonable and it would be a turnoff!
In Mel's case, she was cocky and greedy.