Hard to believe, but some of them are prudes. They just don't want people describing the gory details of their meetings on a public forum.
Yes that, or perhaps revealing gory details which fly in the face of the public image some would wish to project. For example, a website describing a 'high class courtesan', wearing classy dresses and having professional pictures is somewhat tarnished, when the reviewing punter delights in shooting his man milk down her throat and over her face! That profile doesn't read quite so classy anymore, does it?
Some men can be quite squeamish too and may think twice about wining and dining an SP, who they've just read being ragged rotten. So on a serious point, even a positive review can have a detrimental effect on a prossies's business.