Change to a "real" newsreader and eliminate everything from Google Groups.
Like magic the trolls and the Chinese ads all disappear!
40tude is the reader. Like all really great things software it's German.
Just insert a rule: [*] # <-- apply to all groups
!markread Message-ID "googlegroups.com" and you can toggle between seeing
the trolls and not. Use !delete istead of !markread and they are gone
forever from your screen.