If a woman asks me to call her a whore it would be rude to refuse.
Otherwise it's simple: Escorts are human beings that reserve as much as respect as my and your dear mother. (I'm not trying to be kinky here.) If we, their clients, were to join in the denigration, the badmouthing, the stigmatization and the infantilization of escorts, we would not even have the bad excuse of not knowing what we are talking about (which is the unacknowledged position most other people are in).
So I must agree again with the esteemed Julia Sky (comment 6).
Some escorts proudly call themselves whores thereby, I believe, signalling that they don't give a shit about what some ignoramuses think.