It's interesting how this is developing;
Now I did downvote that specific comment, because it was entirely content-free, but as a rule I try not to downvote people responding to me. And the idea of using mass downvoting to harass people I dislike is the kind of passive-aggressive thought policing nonsense which made me stop being a progressive in the first place (seriously, using anonymous voting to shut someone up by making them seem unpopular... how is that supposed to be right wing?).
As far as I'm concerned, the admins are free to look at my karma logs as much as they want, and I've supported anti-karma-assassin software for a while. But politically motivated mud-slinging and invocation of the mods to remove people you disagree with is absolutely beyond the pale. We are supposed to be better than that here.
I have never suspected you, and I am not accusing you of anything. Comments can be aggravating to people who are not the direct recipient.
I'm just tired of the signal pollution, and would like to be able to use karma to honestly appraise the worth of my articles and posts, without seeing 80% of my downvotes come in chunks that correspond precisely to how many posts I've made since the last massive downvote spree.
EDIT to add data points:
Spurious downvoting stopped soon after I named a particular individual (not ALL downvoting stopped, but the downvotes I got all seemed on-the-level.)
One block of potentially spurious downvoting occurred approximately one week ago, but then karma patterns returned to expected levels. I consider this block dubious, because it reasonably matches what I'd expect to see if someone noticed several of my posts together and disagreed with all of them, and did not match the usual pattern of starting with the earliest or latest post that I had made and downvoting everything (it downvoted all posts in a few threads, but not in other threads), so I'm just adding for completeness.
Spurious, indiscriminate downvoting started up again approximately half an hour ago on Sunday (12/1/2013), around noon MDT.
Edit: And now on Tuesday, 12/3/2013, at 10 AM, I'm watching my karma go down again... about 30 points so far.
Edit: And now on Saturday, 12/14/2013, at 2 PM, I'm watching my karma go down again... about 15 points so far, at a rate of about 1-2 points per second.