What about the "worse than a whore" bit? To me, that is the central issue.

The real problem there is the insulting of prostitutes. Providing sexual services in exchange for money is not something worthy of derision.

The 'worse' seems to refer to manipulation. The exploitation of knowledge of another's instincts and the creative use of deception to make them do something that you know that, on reflection, they would prefer not to have done. Some consider that not-ok.