I have a couple of bitcoins in case one day  they increase dramatically in value

A lot of porn sites accept BitCoin but I am sure that the member base of the customers that pays with BitCoin is still small compared to credit cards

But if you want my opinion, you should not be paying for porn anyways. Bitcoin or not

Check out these awesome free sites and you will never need to pay for porn

http://www.xvideos.com/
http://www.xvicious.com/
http://www.xtwisted.com/
http://xhamster.com/
http://www.xstigma.com/