But if you were posting a comment about cooking wouldn't you weigh the Karma of a chef differently than that of someone who has merely joint your culinary community to read up on some recipe?
My experience with comments has been that it is wisest to ignore the reputation of the source and simply focus on the words. (One exception: interpreting irony).
So I doubt that knowing the source of up- and down- votes would be particularly useful either. If I know that a great chef has downvoted my chili recipe, I still don't know whether it is because he doesn't like my spelling, doesn't like my ingredients, or simply doesn't care for chili.
If a chef downvotes your chili recipe, it could be because he doesn't like your spelling, your ingredients, or chili.
If a random person downvotes your chili recipe, it could also be because she doesn't like your spelling, your ingredients, or chili.
The first downvote is still more informative even given any particular reason for downvoting, because the chef is more likely than a random person to know how to spell "roux", cook a perfect pot of pinto beans, or have good reasons to dislike chili as a class of food (e.g. "tried seven versions, don't like any" v. "had it when I was a kid and didn't like it").
[Update: and now there's a fifth discussion thread, which you should probably use in preference to this one. Later update: and a sixth -- in the discussion section, which is where these threads are living for now on. Also: tag for HP threads in the main section, and tag for HP threads in the discussion section.]
The third discussion thread is above 500 comments now, just like the others, so it's time for a new one. Predecessors: one, two, three. For anyone who's been on Mars and doesn't know what this is about: it's Eliezer's remarkable Harry Potter fanfic.
Spoiler warning and helpful suggestion (copied from those in the earlier threads):
Spoiler Warning: this thread contains unrot13'd spoilers for Harry Potter and the Methods of Rationality up to the current chapter and for the original Harry Potter series. Please continue to use rot13 for spoilers to other works of fiction, or if you have insider knowledge of future chapters of Harry Potter and the Methods of Rationality.
A suggestion: mention at the top of your comment which chapter you're commenting on, or what chapter you're up to, so that people can understand the context of your comment even after more chapters have been posted. This can also help people avoid reading spoilers for a new chapter before they realize that there is a new chapter.