Thought this was pretty interesting, according to:
http://www.reddit.com/r/WTF/comments/eaqnf/pardon_me_but_5000_downvotes_wtf_is_worldnews_for/
Jedberg (a reddit admin) says: "The numbers you see are fuzzed for anti-spam reasons. The more active a post is, the more out of whack that fuzzing becomes."
I wonder with sites like reddit/HN if theres a positive-feedback loop, where if a comment has a reasonable number of upvotes it also gets upvoted, or downvoted, if it has negative votes.
It would be interesting to see how fuzzing effects peoples voting behaviour.