It's not the bacon anymore. It is "choose which picture is upright."
Still, this would be difficult for a bot to do on its own (unless it was well programmed), so it's likely that humans are registering the bots, and then letting them take over from there. That means that this rampage shall see no end, because if you make the registration so hard that humans can't do it, then you will see no new members.
In other words, MR's version of verification was only a short term fix.
EDIT: Sorry for the derail there.