Some diarists on dKos rate comments to their diaries; some commenters rate responses to their comments. Both ratings, in my mind, are unethical.
More below.
It is impossible for a diarist to be completely objective about his/her diary. One is naturally inclined to rate favorable comments with a "4" and unfavorable comments with "1" or "2". The same holds true for commenters and their comments.
Rating comments is fundamentally different than responding with a comment. A comment in response to a comment lets the community see your reasoning and assess its weight, and can reflect shades of agreement or disagreement. A rating by the original diarist or commenter, however, tends to be pure reward or punishment. This is problematic, as a comment's rating is supposed to reflect its relevancy, piquancy, information content, and so on, a purpose that can be lost if the original diarist or commenter does the rating.
If comments to your diary or comment deserve rating, let someone else rate them who is not personally involved with the diary's or comment's content. If we are to be the reality-based community, we have to approach our own opinions with a certain amount of dispassion; the community will let us know - for better or worse - whether our opinions are worthwhile.
Comments to this diary are, of course, welcome - but I won't rate them.