If you are that desperate, use a prepaid debit card with no personal information. But using a CC is extremely risky, as these porn sites get hacked every now and then.
1. The debit cards are not accepted for Internet purchases.
The preloaded Credit Cards have the regolar data about the owner.
Payment systems for adult sites are safe and not have the data about caracter of purchases in bills and there are no names of www adult sites too.
If someone enter illegally to some site, it not compromise the personal data of users or make debits on CC holders.
All the CC related data is stored on third side Payment System.
2. The use of Credit Card give the protection for the consumer in case of some fraud site.
Credit Card payments are reversible, and this is more protection for consumer.