I know, 11-12 years ago, maybe longer,  that there were cameras at an in-call location for an agency that did a lot of business.  I am not sure of the particular locations in the apartment but I saw the closet, by mistake, that housed the recorders.  There were 6-8 of them.  Go figure.  I never saw a film of me in action or any of the girls.  I used the agency and that apartment several times.  I "asssumed"  it was for security.  The internet was younger then, but who know.