I have been hearing murmurings for a while about issues with PayPal, credit cards, and various types of erotica. The more taboo forms always seem to get the focus, such as sites that sell pseudo-incest, non consent or dub con, and similar things. At some point, I want to research this more extensively, since I find it hard to form a picture of what's really going on.
But in the meantime, I wanted to call attention to this post from about a week ago, which outlines recent troubles with PayPal and Excessica books, All Romance eBooks, Bookstrand, and others.
Lacking a thorough analysis, the main thing I'm getting is that writers of erotica are extremely vulnerable to this conservative trend from payment companies. Anyone who writes or reads the genre should keep an eye on this.