That’s one of the many reasons I don’t implement a bunch of my side projects, because it inevitably leads to me trying to figure out how to police and remove gross content from whatever website I build, and I don’t want to have to deal with that.
edit: oh no.
But no, I think for the most part it was pretty benign. It looks like they were planning on doing some kind of maybe SEO gaming or something using my de.licio.us clone I made almost a decade ago. I had about 23,000 accounts with .ru and .lv email addresses, many repeats, almost none of which interacted with the app at all.
Many recently created, even today. I think there must be a script that loads in users or something like that.