Yes, I know. I don't remember them from any Usenet groups I used.
Hipcrime destroyed many groups until people worked out how to filter the sporges; snuh made a lot of noise across a wide range of groups but didn't have much effect; Meow army disrupted many groups; and obviously alt.syntax.tactical
The fact that snuh were more disruptive than gnaa is telling because snuh just wasn't very disruptive.