Not only can affiliates not have pornographic sites, the wording is:

"obscene, pornographic, sexually explicit or similar activities...."

And yet, as pointed out by Shmuly Tennenhaus, Linkshare has two programs that fit these categories - Playboy (yep, THE Playboy) and Booty Parlor, a site that sells sex toys. And for 8 years there has been a merchant that sells the extremely sexual "eroscillator".

Double standards! Sites can promote sex toys and porn on behalf of Linkshare merchants, but can't mention such things on their site...