In my opinion, Bitcoin and Porn won't match each other due to the former's anonymity. Yes! Except legit and trustworthy sites like, Brazzers, Naughty America, etc. most other sites will turn out to be scammers and "ad-whores" since you can't claim anywhere that you bought an account there 
What? Bitcoin is perfect for porn sites because of its anonymity. If porn sites started ripping you off then they wouldn't survive for long with such a bad rep. News would quickly spread that people wernt getting what they paid for. Most sites will probably use a bitcoin payment processor too.