One of the things that bugs me is a blog that doesn't allow dissenting opinions. It is their blog, their rules, but I'm not likely to participate if I'm aware. This is extremely common on blogs that promote gun control.
Editing comments without marking the edits is even worse.
It hasn't been an issue yet in the few comments I've received, but I've decided to write up a comments policy. This is in part what I expect from commenters, but mostly explaining how I will handle comments.
Commenters are encouraged to express their views, especially if they disagree with me. I would request that you remain civil, avoid personal attacks, and don't post personal information. Attacking ideas is fine.
In the unlikely event I find it necessary to edit a comment, I will clearly indicate how I edited it, in every place I edited.
I may delete pure spam that is unrelated to the subject at hand, without mention of the deletion. My blog is unmoderated for the first 14 days after a post. I may not approve comments over 14 days old.
If I delete other comments, I will mention that I did, and more than likely why.
If I ban a commenter, I will mention once that I have banned them, in lieu of mentioning every comment of theirs that I delete.
I may change these rules at any time, but I'll publish the changes.