I have noticed a trend on a user who has a history of writing some answers that were off the mark. This user is now catching down votes on good or at least moderately decent answers.
I have previously down voted some answers by the user, that I strongly disagreed with. For the most part I have left a note when doing so. But recently I have noticed, when I read an answer that looks good and has a down vote or two, the same user name is consistently present as the answer's author.
I sort answers by active, and I read the question, then the answers.
I wonder if some of us are prejudging answers based on past experience with an authors work. Most of us who post are doing our best to provide good content for the site. Sometimes I find that I disagree with an answer so strongly that I feel obligated to down vote it. For this particular author I have not had any impression of malice. Just judgment I don't agree with.
Each answer should be judged on it's own merits, not based on preconceptions about the author.
Your votes are yours to use as you see fit. But please ask yourself if you are really using them to benefit the site when you vote.