I took your challenge. The top 5 posts, in order: 1. "There is no nanotech, stop talking about it and start laughing at it". Top comment: jacqquesm. Character: sceptical ("Nano machinery is real, it exists, it powers the world, it's called biology.") 2. How to minimize politics in your company. Top comment: abalashov. Character: critically supportive ("There are certain problems [...] that simply cannot be solved or…
It's not just that giving a voteworthy supportive response requires domain knowledge — you also need something to add to the original article. I've seen lots of good articles on topics I know about, but usually I'll just upvote rather than comment because the original article did a fine job by itself. If I do comment, a lot of the time it will just be a minor clarification or tangential thought rather than something that merits a lot of upvotes.
Skepticism, on the other hand, is automatically something meaningful you can add.