Here's a fourth factor: people upvoting before reading it (but possibly after skimming it or being aware of it's context) in order to keep it highly ranked (whi

Here's a fourth factor: people upvoting before reading it (but possibly after skimming it or being aware of it's context) in order to keep it highly ranked (which is score + time sensitive) in order to trigger HN discussing the subject. I was in that camp before it got flagged.