This is nothing new and honestly it was much worse in the past. It's just some idiots who have a bot that goes around attempting to create or break into accounts on any forum they can find. If/when they successful, they post their spam advertisements until they get banned.
There have been about 8,000 attempts to break into accounts in the last 10 days, and there's no telling how many accounts they've tried to create in that timeframe. We have processes in place to stop them, but it's obviously not perfect. They get through every once in awhile, and it just so happens that a couple weeks ago was one of those times. No big deal, we removed at least most of their garbage accounts, but they keep trying.