As soon as someone sends a picture of their private parts before even meeting you in person, any expectation of classy behaviour should go out the window. His following behaviour was not at all surprising and it seems pretty obvious what he wanted. Some glaring red flags went unnoticed here.

Also, wouldn't you prefer that a guy was straightforward with what he wanted rather than pretending to be interested, sleeping with you, then leaving? At least he was honest about his intentions from the get-go, and there isn't necessarily anything wrong with wanting dirty pictures if both parties are in agreement.