At the expense of becoming public enemy number one, I have decided to post a grumpy post. (It was rather grumpy when I first posted it, I hope it reads better now.)
This is hardly a new call to action, but the last time we had a meta discussion on this topic was quite long ago.
Overview
Votes are the primary mechanism by which the quality of questions and answers are established. Every day, we have 40 votes to use. However, even the most prolific of voters on here barely use one-fifth of their available daily votes (SEDE query).1,2
Downvotes
I feel that, in general, we give out too many upvotes and too few downvotes.3 One can also see this in the query results. (I must say that I am not sure if the results include votes on deleted posts. If it does not, then I would expect the up/down ratio to be severely skewed towards upvotes, as it is right now.)
However, that is not my impression of the front page. A lot of things that arguably deserve downvotes get passed over and ignored, hovering around a neutral score of 0.4 Closing a question, or deleting an answer, often takes several hours since we do not have a lot of people here. Downvotes would help to clearly signify that such questions are not welcome here.
I hope that we do not refrain from downvoting merely because we are afraid of hurting somebody's feelings. Downvotes are not something that you or I should be ashamed of, especially if the content is objectively bad. Examples include: entirely wrong answers; one-liner or otherwise poorly substantiated answers; zero-effort HW questions. I would also like to point out that downvoting questions costs no rep and downvoting answers that eventually get deleted also costs no rep.
I have removed the paragraph that used to be here, because I do not want to specify or dictate what should or should not be downvoted. That is something that everybody has to decide individually. However, the point still remains: we as a community need to judge post quality more.
But downvotes are rude and not nice!
If you feel that a question has potential room for improvement, then please leave a comment saying whatever you feel is relevant. It doesn't have to be a really long essay, even a short comment gives people some feedback and sometimes it does lead to the question being improved via editing. This meta post may help as well.
Upvotes
With that said, not all content is bad. Every day I also see good questions that only reach a max of +2 or so. Please do upvote good questions by new users (there are many of them). As a bonus, it also motivates us to write good answers to them. Here's an example of a good question.
I think that, as a first rule of thumb, if you could envision a question receiving a good answer, then it is worth upvoting. Of course it is more nuanced than that, but I feel that that is a good starting point. And if a question already has a good answer that you upvoted, do upvote the question as well! If you think the question can be further improved, edit it! Our entire purpose is to create and curate good, quality content. I know I ranted about downvotes signifying bad content, but we also need upvotes to signify good content, and not only on high-rep users' questions/answers.
Footnotes
1 For those who don't understand the SEDE syntax (like me before this afternoon), this query lists the top 100 Chem.SE users by their votes per day. Only users who 1) were active in the last 30 days, and 2) have 100 or more total votes, are counted. This is to get rid of outliers, for example, someone who registered yesterday and voted 5 times.
2 I know that this is an inherently flawed query. It does not account for periods of time where people are away from the site, amongst other factors, and I wanted to try to construct a query for votes in the last 30 days, and I'm sure that would show higher voting rates, but I believe SEDE doesn't allow me to pull vote times, so this is the best I can do.
3 I am not trying to call out any particular user or their voting pattern, so please do not take it that way. I am glad that there is lots of content that we upvote, but we just shouldn't ignore the rest.