Is this fair, morally right, or acceptable? By really old I mean at least a month or two old.
People are perfectly entitled to use their votes however they like, it's something of a democracy - if there's an answer you don't like then do as you please, I routinely up-vote really old questions and answers.
That said I'm always wary of users who focus too much on personal rep or that of others, this is a Question and Answer site, not a rep-building site. Sure I take interest in my own rep when I'm near certain milestones (8192, 10k, 16384, 32768 :) ) but otherwise it's my belief that it's the Q's and A's that matter, rep is just a byproduct.
Because I only ever view the front page I only see a small percentage of questions when they are first posted. When I see questions, together with any answers already posted, pushed back into my sight I treat them no differently than if they were freshly posted. Why should I?
In regards to your choice of words:
- SF, and Stack Exchange in general, is "fair" only in the sense that by and large voting is done honestly.
- Morality is a very personal thing and yours and mine will very likely differ.
- Why on Earth would you imagine that it might not be acceptable?
Your tone and even the question itself suggests to me that you feel slighted by someone (possibly even myself) having downvoted some of your "old" posts. If that's the case maybe it's time you started reading what you're writing and make an effort to improve it. Just like upvotes, downvotes are generally earned.
Generally I would say only downvote a question if it's a lousy question. The same holds true for answers, and is regardless of age.
Sometimes I will troll through the "unanswered" old questions in tags I have a particular interest in (to see if I can answer them, or if they've been answered but nobody upvoted the answer, or any number of other things). I vote on those questions/answers the same way I would if they were new.
It's fair, morally right, and acceptable. Depending on how you look at SF or any other SE site, you're quite likely to come across old questions (bumped by Community, listed as Related to a current question, browsing a particular tag, looking at someone's asked or answered list, and so on). In many cases, if it was a good question or answer a month or a year ago, it's still good now and there's no reason not to vote. That said, if I'm reading something more than a few months old and it's already got upvotes or downvotes that I agree with, I won't necessarily bother to add my own.