Every now and then, I find comments which I like. Were I on facebook, I would put a like. Here on SX, "like" is not an available feature. The closest I can think of is upvoting. Sometimes I do, sometimes I don't. I have seen humorous comments with many upvotes, so I guess this is not too bad an idea. However, upvoting should be used to mark constructive / useful comments. Some comments I would "like" are decidedly not constructive nor useful. Is it advisable to upvote such comments or should I just leave them alone?

• The rules of the site are greatly ignored by the community in many respects. So first I think you need to decide whether you want to follow the rules or follow the flock. Once this is decided, the answer is easy. – Git Gud Sep 24 '14 at 12:16
• Since you are asking specifically comments (not answers/questions) I have added (comments) tag. If you want to make this information more visible, you can mention it also in the title. (For example: Upvoting comments as...) – Martin Sleziak Sep 24 '14 at 12:28
• Put likes on them to your hearts content. Nobody's gonna stop you, and you never run out of comment votes. – Jyrki Lahtonen Sep 24 '14 at 18:49
• @JyrkiLahtonen The limit is 30 comment votes per day, but few people ever reach it. – user147263 Sep 24 '14 at 19:09
• Really? I believe you, @CareBear, but this was news to me. And I think I vote comments very often :-) – Jyrki Lahtonen Sep 24 '14 at 19:10
• @MartinSleziak: I went ahead and added it to the title, because I found the question without it confusing, and it seemed pretty obviously in line with the original author's intentions – Ben Millwood Sep 27 '14 at 17:51

On the main site, $5$ top voted comments are shown; on meta sites, $15$. So, if one particularly funny comment gets upvoted to the skies, no big deal. If there are several, and they are crowding out less funny, but more useful comments, there is a problem. Withholding upvotes, or flagging for a moderator to delete obsolete / chatty comments, is appropriate then. For more, see A guide to moderating comments.