I think your conclusion that something is rotten in Durham in relation to the free operation of prostitution is spot on, although I'm not sure it's the courthouse crowd.
The statistics you posted speak for themselves. It's pretty clear graft is going on. Should anybody decide to start an investigation, the vice detail with DPD would be the place to start.
My thinking on the CourtHouse Crowd is that like any bureaucratic organization, very little can be kept secret. Maybe a lot of them weren't in on it, but I'll wager most of the Crowd knows about it...