I've been thinking about this most of the day. This represents, like you said, people with nothing better to do, grouped by how much the user dislikes a community.
You could take action targeting these users. BUT, what about sneakier brigading. For sure there will be users with even MORE nothing better to do.
For example, if they have multiple accounts spread across multiple servers and automate downvoting?
Maybe, a super simple solution is to rate limit downvotes? I mean it's not elegant, but if it were slow enough, it prevents burying things.
Your right. You just asked what a "fake account" was though. I think it's generally accepted that if you create "alt" accounts for the sole purpose of vote manipulation, you're being a dick.