If you just make it a “playboy” type portal, as far as look and feel is concerned, it may work. I will be niche and attract mostly males. Not sure what the exact demographics might be, dunno much about porn.
I wouldn’t carry actual sex ads, that confuses the issue. Just a certain look and feel. But, while it may take you a while to establish the niche, I am always for doing something different. All the portals out there look all the same and seem interchangeable. You would be more memorable.