We don't really know much other than it being some guy with no life. Sometimes they get bored and stop spamming for months, then suddenly we get like 20 accounts in an hour. It varies a lot.
Spam bans are easy as shit and take literally 4 clicks (account, ban button, marked for spam, buh-bye asshole), so we don't really find it deserving too much public attention. Hell, not even all mods know how many porn spammers we banned. We don't keep a record, he's just another faceless account for the gallows.
It could be more than 1 guy, it could be the same guy. We had threads "Hahaha I am the spam guy and you will never stop me" in different tones from wanting their old account unbanned to simply not caring and wanting to make fun of the mods.
Best you can do is hope their balls drop in due time.