Well, I'd say if the site is about selling porn, content is much more important and the colouring should be kept at a minimum. I prefer sites which stick with two or three colours. Anything more is like looking at a candy shop. When I shop for porn I usually get the impression that a site isn't a serious business when there is too many colours. There are very few exceptions, but when colours are dominant I tend to believe that the content isn't good enough to speak for it's own.

However, if you want to sell colours... it's a different story of course.

But that's just me and my two euro cents. $0.02