Ask HN: Are HN downvotes appropriate for mere disagreements?

I realized that the HN Guidelines page does not talk about downvotes. I want to solicit some community-wide consensus on when downvoting a comment is appropriate. I'd like to broadly categorize comments into several types, arranged in order of appropriateness to use downvotes:

1. Anything that's not constructive or not in good faith. Trolls, personal attacks, etc.

2. Anything that's interesting but off topic.

3. Anything that's relevant and interesting, but the comment has factual errors.

4. Anything that's relevant and interesting, but primarily opinion-based and you disagree with that opinion.

I noticed that I sometimes perhaps downvote a little too much. Perhaps we should standardize on only downvoting 1,2,3 but not 4? Or perhaps we do want to downvote all four, or only the first two? Any thoughts?