Not easily, no, but I think a very fast reply frequency, especially between lots of pairs of two people, is more indicative of heat than light. :) (who knows, maybe the algorithm will think that about this reply) Genuinely interesting topics probably require more time to write worthwhile comments on, and draw in more people.
(To be clear, I'm not implying nor do I think that HN uses raw comment-count as a signal of overheating, just expressing my surprise at the previous poster's surprise at seeing high-ranked stories with few comments, since the correlation should run the other way if at all.)
