Something I notice is when there's an advanced/specialized question, it often receives very few upvotes. Even if it is seemingly well written. I try to upvote advanced questions that I might not even understand, if they appear well written.
Is this good behaviour? Should we encourage upvoting seemingly well-written questions even if you don't understand it?
First off, you explicitly mentioned this suggestion a while ago, and the community seemed to think it is valuable.
That said, as the comments imply, it can be a little risky... but I don't think it is a significant risk. From my personal experience, any "nonsense" is swiftly dealt with by the community, regardless of how advanced it is. I don't know if this should be intuitive for some psychological reason, but people seem to be more active towards things which are significantly wrong than giving praise for something (for better or for worse). Furthermore, advanced topics will naturally have a lower rate of nonsense (or simply be completely nonsense, spotted even by people who don't know about said advanced topic), merely because of the level of intimacy with mathematics as a whole that it requires.
So, I don't think the risks are significant at all. However, one pertinent question remains: "what is the goal on doing so?"
It is a fact, no matter how we try to mask it, that reputation points are valuable. Be it because of the points numerically, be it simply because it is a ratification of the fact that your spent time was recognized by someone else, or some other reason which is specific to each one. If you spend time somewhere and you get no feedback on it, this will eventually wear you out. And this may eventually decline the number of answers/questions on specific topics. Likewise, if questions/answers on a topic are upvoted, there is an underlying motivation for them and also a feeling that said topic "is alive". This is less abstract than it seems.
Having made explicit my opinion of the little risks and of the goal, I say that this can be a good behaviour for the site... but I don't think this should be encouraged to the community as a whole, since an en masse upvoting of this sort could be potentially disruptive (this would never happen, but...). It also has "ethical" problems which were mentioned in the comment: upvoting something can be interpreted as you signing your name (anonimously, as oxymoronic as that might sound) under the post saying it is good quality. If you don't understand what you are signing under, this is bad. If you don't think of upvotes that way, I think you are fine.
I think that the general guidelines for "asking a good question" on this site are nearly content agnostic. I might write a horribly thought out and poorly reasoned question about category theory which belies a fundamental misunderstanding of what a morphism is, but that isn't grounds to call it a bad question. The only real reason a question might be a bad question and require you to know a lot about the subject is for the question to be so fundamentally confused that it's unclear what is being asked. However, I think that this is generally a rare phenomenon and so I would be comfortable with people upvoting questions based solely on their non-mathematical content, such as their context, attempts at work, formatting, and length.
Not a perfect remedy for precisely this issue, but a nice feature that would help with this and bring other benefits for the community, would be to give a few users exceeding some reputation threshold or some maths skill threshold (e.g. holding certain badges) limited numbers of say $+5$ votes.
Not sure how well the sits with the idea of democracy.
To some degree I've seen users use the bounty functionality to this end which impacts reputation but doesn't have the same longstanding effect on question rating.
Should we encourage upvotes on more advanced questions, that are seemingly well written, even if you don't understand it? ... Is this good behaviour? Should we encourage upvoting seemingly well-written questions even if you don't understand it?
The lack of voters for some questions is discussed here: Why aren't people voting for questions? - at length. If it's a bad question it should get voted down, if it's a good question (see: How to ask a good question?) it should be voted up. If you don't know don't be embarrassed (no one knows) just move on, you don't want to upvote nonsense.
It would be great if there was an "Interesting Questions" Tab that Mods and a group of designated experts could tag questions for, so the question would get more exposure (without necessarily having many views or upvotes).
If Mods could be given a "Bounty Wallet", so they could add a bounty to a question without pulling the cash from their own pocket, and a question received an "Interesting Question" flag from a single person (from a small group of designated experts), the wallet could supply a couple of hundred rep to at least get the question some views.
The actual upvoting should be reserved for the so-called "good question" (as understood by the voters).
A prime example is some people can take a good photo or are skilled at Mathjax, that doesn't make the question they ask useful or good. Some people need help taking photos or using Mathjax, that doesn't make their question bad or not of general interest; unless it's a FAQ or dupe.
A means to toss a 'good question' with few views or voters into an additional Tab, even to push it into the "Hot Questions" (when it's cold), would be helpful.
Voting for things you don't understand (up or down) puts an odd spin on the ball. You wouldn't wash your neighbour's car if it looked dirty, walk their dog if it looked lonely, take their wife out to dinner if they appeared hungry - if you shouldn't mess with stuff you don't know about then don't.
Those points were made in the links listed, if you're going to answer why not upvote the question, if you choose an answer why not upvote it also. If you don't know that's OK, but adding random votes or answers doesn't help the majority.
Unfortunately the asker will have to ask 'popular' questions for more votes and easier questions for more answers. Spending 10 minutes to get 10 rep is something each must decide for themselves if it's worth it.
