Only stick with .com / .net / .org / and if desperate .info (infos can rank).
But even if you did get a good domain, don't think you can slap adsense on a adult related domain. (I see you comparing with Adwords, and CPC so Im guessing youre going to slap some Adsense on it). Your account will be banned real quick. CPC is fail for most adult sites. And for most niches, you're looking at selling PPV, selling ad spots, or affiliate through ccbill/pay sites/cam sites. To make money in adult, you MUST have a shitload of traffic, bottom line. They are monetized through affiliates (talking about 'real/legit' adult sites) mostly cause thats where the money is.
Depending on the keyword, they can be very competitive to rank for, so beware of that, especially broad keywords such as Porn, Sex, XXX, free porn, free porn videos.
You should also be aware that adult traffic is worth way, way, way, way less than normal traffic due to the fact that everyone wants free porn and its readily available and converting is very hard. But on that note, I can say that with the adult niche, its easier to get more traffic. If youre not pushing cam sites (or theyre not converting) Expect a good 1cent per 1000 page views with offers.
