I'll throw this out there from my experience 5 or 6 years ago.
I went from being a broke college student just selling porn part time 1 year (and barely able to make the rent), to grossing over 300K the next year because of the concept of "review sites" and what makes them so profitable.
Granted, this was before rabbit, adultreviews, porninspector, thebestporn, and all those were anywhere near top 10K alexa, and the SEO traffic was soooo much easier to get for people searching for site names. This was also when reality porn was new and hot. I literally had a half page ad per review, few sentences of text, and agressive SEO, and after 1 google dance update things went from not even $100/day to well over $1,000 a day, practically overnight! It was awesome and alot of money for a 20 year old full time college student who knew SEO and had a limited adult network to accomplish.
Would I start one today? Hell no. It's too competitive, over saturated, the affiliate side is hurting in general, and to be anything more than a small fry would take way more than I'd be willing to invest on a gamble. Nope, if I came back to adult, review is not where I'd go.
