I think that many people post jokes here because on other similar sites they're an easy way to get (often quite a lot of) upvotes, and a lot of us here dislike

I think that many people post jokes here because on other similar sites they're an easy way to get (often quite a lot of) upvotes, and a lot of us here dislike that mentality. My criteria for upvoting a joke are generally the same as my criteria for upvoting any other comment: if I feel it adds something to the discussion, it gets an upvote. If I feel like it contributes nothing at all, it gets a downvote, because reading it is a waste of someone's time. Most of the jokes posted here are surface humor. They are relatively obvious and add nothing to the discussion, and so I downvote quite a lot of them. Occasionally someone will use humor to make a good point, and then I will upvote them. In general I'd discourage it, though--it's usually much easier and clearer to just say what you mean, and people here are usually receptive to well-argued points.