I stopped taking them when they first appeared, and the "mature" ones are only part of what I had against them.
The incest sites from the same sponsors and the "older man - y0ung g|rl" ones are the ones that really push the line..
Additionally the sponsors themselves do some "bad" stuff in the search engines
You get lots of them... as most are free hosted and they give away large amounts of content..
Part of the reason they are "popular" is that they "are" well targetted at the market with content to suit the "Mrs Robinson" fantasy.
DD