If someone spams using the same user id, presumably we can block or deactivate that user. You would have thought that a spammer, on seeing their posts get removed within hours, and only getting a small number of views, would realize how inneffective it is as a marketing channel and stop doing it. But that assumes people are rational, and that the post is done with human interaction as opposed to some automated bot.

Moderators have and use the ability to ban an user and to delete all their content, David. I would like to see more to be elevated to Moderators. You and Ian come to mind. 

I have no objection if you want to make me a moderator. :-)