and of course the americans will do it single handedly because they own everyone rofl

I don't think this is actually a new stuff, responsible adult webmasters always add warning etc to their sites.

I've always liked an idea of having META tag for a sites content, so say it was adult...

<meta category="adult" />

So you could easily allow browsers to block the sites without messy filtering software. (Granted not all webmasters would obey the rules so you would still need filtering software )

Yes you have a good point about some webmasters not complying with labeling the site correctely, this is actually one of the reasons I supported the creation of .xxx domain, it will make it easy to filter the entire extension.