I have doubts as to how much damage one person can do to another with down-voting, even with sock puppets. Looking at my own posting history, I have made 248 posts which have received a total score of +1634, for an average of +6.6 per post. I assume I'm pretty ordinary; the most I've gotten for a post was +26 (for what I thought was a fairly routine bit about web servers and CGI -- not even directly about Perl, oddly enough) and my least was -1. (Which appeared to get two -- votes because I implied that negative look-behind is a "recent" regex feature. Oops.) No really high ones or really low ones.

So anyway, to give me 15% negative votes, as chromatic reported above, my arch-enemy would have to vote at least once on every single one of my posts. That would be too obvious if he did it from a single account, so maybe he'd divide it up with a couple sock puppets. Then, so it still wouldn't be obvious, he'd have to down-vote some other people too (and really, is the kind of person who would do this likely to only have one target?). Then to keep from getting penalized for too many down-votes, he'd have to spread around a lot of up-votes to other people -- and not just to his sock puppets, or that would be obvious too.

So I'm guessing that to make it work and keep the accounts functioning and avoid getting caught, he'd have to spread around a dozen or more votes for every negative one he gives me. And I'm not that prolific; I only post once or twice per day. To keep up with someone who posts several times a day, he'd have to spread around several dozen votes. That means more time, and even more sock puppets, just to have enough votes to keep up.

I don't know; maybe I'm not dastardly enough, but it just seems like way too much work to me.