Firstly your keyword should be related to your domain name. There are high paying adult keywords, but if it is irrelevant to the domain name, you will see a low CTR and it gets pointless having a high paying keyword. Can you tell me your portfolio adult niches? Like maybe mature women, g*y, erotica etc?
I had started getting some 22 cent clicks on a g*y adult keyword at Sedo. Its now been reduced to 5 cents..lol. But I do get 90 cent clicks at PP for some gran*y keywords. Send me a pm if you wish.