It's a massive problem! I don't think we can consider it "solved" by keeping it off of popular relays and content hosts, though.

This is one of the major reasons I don't run a public relay. Most relay implementations have no way for me to keep this garbage off of it. That being the case, the most I will run is a WoT relay where I can be relatively certain the folks who can post to my relay won't be posting anything like that.

Relay operators need better tools for reviewing and acting upon reports.