Comment by nick__m
8 days ago
Submit interesting unique links and post more substantive comments (maybe add a paragraph or two your previous comment) and you will be able to downvote soon enough. But I don't understand the appeal, when I do it is usually accidental (really easy to do on a tablet)...
I usually downvote comments that are derailing the thread or are so lazy as to feel like a waste of my time to have read.
I'll often upvote comments with opinions that are counter to my own, especially if they are presented in a clear, coherent, or novel way that causes me to think a bit.