> I don't see why this is particularly damning. Visit any porn tube site right now and you will notice that "teen", "stepsister", and a few other young-sounding keywords are incredibly popular. The actresses are quite obviously NOT underage.

> When I worked for kink.com a decade ago

Commercial "underage" content can get away with it because they always have the 2257 records to back it up. That's as much a certification of its fictional status as one can get.

There are no 2257 records for prostitutes. And prostitution itself is illegal. When you're at the point where you're setting up filters to govern the facilitation (not prohibition!) of an already illegal trade, obscuring the fact that ad subjects for non-fictional services may also be underage doesn't buy you any deniability.

Once you demonstrate knowledge, it's game over. That company selling encrypted phones to cartels, the guy building smuggling compartments in cars, Ross Ulbricht, and now Backpage...all demonstrated that they knew what business they were in and did it anyway. Hell, pre-legalization, the stoners at your local bong shop had better OPSEC than most of these clowns-- you mention marijuana in their store and they'd kick you out and refuse to do business with you, since they didn't want to be caught admitting they were selling drug paraphernalia, just "tobacco pipes, man."