Then you'll see the common entry point to that network and untag it. Maybe your uncle's friend (who is secretly a spammer) tagged a bunch of bots as family members so you cut off your uncle's friend. Or your uncle, if he has a lot of these friends.
It probably won't work in reality but that's the idea.
That's fine, it'll all be left-handed whuffie (in Cory Doctorow terms) because although they'll all tag each other, they won't be part of my tag web.
lobste.rs has an account tree thing. I don't know how well it works at all, but maybe in a worst-case scenario the moderators can get rid of an entire subtree, at the cost of some collateral damage.