I was trying to figure out the total number of answers I have that have been downvoted, and at first everything seemed awesome since the total was zero.
However, I knew this wasn't correct. For instance, look at the following query and result:
https://api.stackexchange.com/2.0/answers?pagesize=1&order=desc&sort=votes&site=gaming&filter=!*K.0.GUmNraMAdY_
{"items":[{"question_id":44595,"answer_id":44600,"score":138,"is_accepted":true,"title":"Is Angry Birds deterministic?","up_vote_count":144,"down_vote_count":0}],"quota_remaining":284,"quota_max":300,"has_more":true}
The "score" is 138, and the "up_vote_count" is 144, and the "down_vote_count" is 0. I had thought perhaps just the down_vote_count was wrong (as I knew it was non-zero), but the up_vote_count is also incorrect.
In reality, the answer is at +141/-3 for an effective score of 138. The score is the only correct part.