I never downvote anything anywhere ever. I don't understand how can downvoting make any constructive sense. You are meant to flag whatever is spam, offense or blatant misinformation anyway.
I also believe many people would feel very bad if you downvote them so you should better have a serious reason. The fact you disagree or don't like them (let alone don't consider what they wrote interesting/useful for you) is not enough.
>>qwerty+(OP)
I was about to say you can't flag comments so downvotes are the only option, but I realized I have only been assuming that for years and never really questioned it. Looks like if you click on the "n [minutes|hours|days] ago" link on a comment, there is a "flag" option there. Now I know. So the questions is, why even have a downvote button?
>>qwerty+(OP)
Probably part of the reason people downvote is that the button is one click away, whereas the flag button for comments is two clicks away and probably many people aren't even aware of it.