I recently read "The Alienist" which is the fictional story of a killer murdering underaged boys who dressed as girls at brothels around New York City. It takes place in 1896 and one of the things that shocked me is how many of these brothels there seemed to be and how their existence was accepted by the characters in the story. I know the author Caleb Carr was a historian himself so I'm wondering how close this is to reality.
I hope this won't preclude another answer, but I posted an answer about The Alienist's depiction of child brothels and child sexual exploitation in a recent Saturday Showcase that might be relevant to your question.