Craigslist used to be the wild West. You could find practically anything there. The problem is it wasn't regulated much, if at all, and people got up in arms that it contributed to things like prostitution, child trafficking, drug dealing, etc. But most of the ads were for other things. But that was where shady porn producers and other "adult" services used to advertise and recruit. After a while, a prosecutor in California thought it'd be a great idea to threaten Craigslist, so they took all those kinds of ads away and they went to Backpage.com, which was owned by two local guys who ran a chain of weekly alternative papers.