I assume that you are contemplating the possibility of running a classifieds, reviews and forum site in this niche, as that is where the money is. It seems to me that the territory comes with some danger zones in regards to legality and ethical boundaries. Especially when it comes to age/minors, human trafficking, slavery, geo-restrictions and a plethora of nasty topics that such site would need to steer well clear off. Which would mean strict rules and strong proactive enforcement and prevention. Just opening a site to see what happens seems likely to me to end up in highly unwanted situations. Just like you don't want international arms deals by conversation on a gun forum, its easy to see how things could go wrong for an adult provider site. The fact that such issues need to be on the radar also indicates a social element. It would not surprise me if there would be a role for helplines and organizations that help people who are caught up in nasty situations.