Have you guys ever seen stripper or escort websites that cater to female members of those professions? There are a few of them out there, and they exist primarily so that strippers and escorts can communicate with each other and get better at their jobs. These sites have to be sexual of course because the subject matter is sexual (stripping, escorting). But because they are run by and for females, they are definitely set up in a different way than they would be than if they were for men. Sort of like a lot of people have already said, these sites aren't really plastered with pervy pictures. A lot of the strippers have pictures of themselves on their profiles, but the pictures are really more about them looking hot than they are about specific sex acts or anything. When sex is talked about it's in more of a clinical fashion, and not in a pervy way to get guys off. For example, a woman might ask a question like, "How much should I charge a customer to make out with me?" as opposed to the way a guy would word it, which would be more like, "Dude! I just made out with a stripper for like an hour!"
So my guess is that when women design sex-oriented websites, the content is less overtly sexual, less "pervy," less graphic, or at least graphic in a different way. Women seem to like sexuality when it empowers them, makes them feel hot and sexy, while men primarily want lots of very intense visuals, and lots of T&A.