I don't really have an opinion of Dr. Brooke Magnanti, either. I've only read very small bits of her blog and have never read her book. Ive never evens watched the TV show. I do think she has plenty to back up her story (I read a long and sort of ranty blog post where she refutes claims by someone or other and seems to have a convincing argument) and other prostitutes I know say that her experience sounds very familiar to their own.
As to why someone would lie about any such thing, I don't know but I do know such things are possible. There are definitely misery peddlers of all sorts, and some of them have been exposed as frauds. It seems that their chief motivation is sympathy or just attention. I have no way of knowing that Rachel Moran is one of those and I would agree that the ordinary correct thing to do is to take people at their word. I just know that she says things that sound bizarre to me. Her pinned tweet is "I answered phones in enough brothels 2 know the most common questions is always "What is the youngest girl you've got?"" While I have never been a teenager working the street I have answered plenty of brothel telephones and never been asked who the youngest girl on the rota was. The bustiest girl, yes. Never the youngest, to my memory.
Since in a heated debate where personal testimony is often key, the discrediting of the opposition on a personal level is a very common tactic and while it may sometimes be useful (if the person is a demonstrable fraud) I think it mostly only makes the entire discourse toxic and useless.
It hasn't happened to me personally, but I know that one way the voices of the Happy Hookers is attacked is to claim that we are actually pimps in disguise or pawns of pimps. As far as I know, everyone who spoke at the conference I went to who claimed to be a prostitute was someone like me (I know their work identities and have seen their AW profiles) Everyone else there seemed to be an outreach worker, a public servant (politician, prosecutor, law enforcement), or an academic. I have heard accusations that some of the voices on our side of the debate are the voices of pimps but I don't know if they mean someone in particular or if they're just generally discrediting in a vague way.
It would probably be tempting to wave away anything I say by saying either that I am being put up to it by someone controlling me or that I am deluded and don't know my own mind. That sort of accusation would probably make me angry and I would struggle to maintain my civility and composure. And so the debate would suffer from that.