The only people left will be the Christian fundies cancelling all the science groups, because I doubt the scientists will care enough to cancel back. Even the toys newsgroups get people antagonised to a point where they'll start cancelling all the posts out of spite. You don't even merit a newsgroup with that traffic. I suppose chat systems will be the next thing to be hit by advertising bots. You ignored the conventional wisdom - moderate the goddam group.
Spammers just fake the moderation then.
For best results, view this with Linux.