I've noticed that when I ask a question on MathOverflow, or any StackExchange Site, and I either upvote or downvote an answer written by a high-reputation user, regardless of how old the question and answer are, I very frequently get a corresponding upvote or downvote on my question shortly thereafter. I assume this is because high-reputation users can see who cast the upvote or downvote, and they reciprocate the questioners' vote.
First of all, is it true that sufficiently high-reputation users can in fact see who casts the vote, is it true that some of them engage in this practice of "reciprocal voting", and is this an acceptable practice? Personally, as far as I can tell, the upvotes and downvotes I've received as a result of it have pretty much cancelled each other out, or maybe redounded slightly to my benefit in terms of reputation. (Assuming this is all not just in my head.) But is it fair for the vote count on a user's question to reflect how the user has voted on the answers?