Medfet in literature

I was rereading a murder mystery novel originally published in 1997. It is called 'The Magician's Tale' by David Hunt and is set in San Francisco, with the main character an achromatic color-blind young female photographer. This means she can only see everything in shades of black/white/gray. She is engaged on a photo book project documenting male hustlers, cross-dressers and prostitutes when one of her favorite models is brutally murdered.

All straightforward, but in one scene she and another hustler are casting about for likely perpetrators of the murder, and the hustler tells of one really weird customer who is known around. He is a doctor, supposedly a real doctor, who likes to pick up male or female prostitutes to take them back to his office where he conducts long and lengthy and intimate examinations of all kinds, one of the more outrageous supposedly being proctological exams.

This is one of the few times I've encountered anything in real-world literature that is related to medfet of sorts. And even though the book as a whole is very enlightened about all kinds of sexuality and sub-cultural groups, it looks like medfet situations still come under the category of very weird and suspicious and worthy of a homicide investigation ...

I guess there may be references in other books, but so far this is the first I can point to.

Btw - the book is very intelligent and captivating. The author obviously knows photography and the ins and outs of the grimier parts of SF.