On a programming topic, on HN, maybe 20% of the comments are interesting, or at least informative. On a programming topic, on Reddit, maybe 2% of the comments are interesting or informative, but there are 10 times as many comments, the interesting ones are voted to near the top (not necessarily right up there), and some of the interesting Reddit comments don't have an analogue on HN.
/agree SNR on reddit mebbe 5%, slashdot %1 here, I don't know 50%? I see some less than useful posts (like this one), but almost no outright trolling/patently wrong posts.
HN makes my daily read list, even if it is a quick glance. Great community.
