You have to pay the porn sites with credit card, because paypal doesn't allow such things. There are very strict in the business field. So master card or no porn my friend
It can be done. Chaturbate uses PayPal (via Epoch smoothly). Not sure what the rules are here. Maybe its fine to give money to people via PayPal, who just happen to be naked.
Looks like you can use them from processing adult now but ONLY INDIRECTLY. You add Epoch as your merchant, and they'll offer PayPal alongside with credit cards for the customers. Source: there's a big list of PayPal porn sites here now: https://x3guide.com/billers/paypal-via-epoch