I manage an entertainment site that contains a great deal of original content. A fraction of the site's pages and posts contain photos of celebrities and known models wearing bikinis.

Adsense messaged me a link to one page with such content, pointing out:

Google ads may not be placed on adult or mature content. This includes any site which contains:

full nudity
pronographic images, videos, or games
pronographic cartoons or anime (hentai/ecchi)

For more information about keeping your content family-safe, please review our program guidelines and these tips from the policy team.

So I removed the content from the site. A week later, that particular site was banned from Adsense (though the account as a whole was not banned). So I reviewed their program guidelines once more:

The AdSense network is considered family-safe, which means that publishers aren't permitted to place Google ads on sites which contain #*$!ography, adult, or mature content. If your site has content which you wouldn't be comfortable viewing at work or with family members around, then it probably isn't an appropriate site for Google ads.

I have yet to find a concrete answer from Adsense online as to whether or not bikini pictures specifically violate their program policy. I'm talking the same kind of pictures you can find in magazines at your local supermarket. The same kind of swimsuits you see every time you go to a pool or the beach (where people go with family members).

How can anyone tell when you've moved into "adult content" territory?