Maybe I'm unusual, but I don't pay attention to others' karma scores that much. My own experience on Reddit and HN has shown that karma scores have more to do with early-entrant effects and brevity than the quality of the content.
Many of my best Reddit posts, in my personal opinion, are at 1 or 2 points, just because they got buried in huge threads. Whereas I have one-liners that took me literally 5 seconds to come up with and ended up at 100+.
If I were to make an automated system for judging quality of message board content, it'd be a function of text readability (grammar/punctuation, avoidance of overly-long "text wall" paragraphs), size, and user feedback. A 500-word post with 7 upvotes is probably more awesome and more deserving of prominence than a 10-word one-liner with 125 upvotes.
