Recently we've been hit by a wave of extremely low-quality questions, mostly from unregistered accounts. A few examples (all deleted):
There (a lot of) others, I've highlighted only ones from removed accounts. Those accounts where all unregistered, obvious throwaways, and one way or another the IP trail lead back to a known and exceptionally persistent network-wide troll. I've already contacted Stack Exchange to take a closer look at the remaining accounts.
One thing we could do is stop accepting questions from unregistered accounts. It's not a great option, but it will add a little bit of friction for our troll. The downside is, of course, that we may miss some legitimate questions from unregistered accounts, like these: