Placid Point and the Rules of Self-Publishing

Over the past year or so, wisdom has been accumulating in the blogsphere about who should self-publish, what they should self-publish, and when. The advice seems to amount to this:

If no-one else is going to publish it (because, say, it was commercially published once but is now out of print, or it's new but your agent can't sell it) ANDIt is good (which you can tell because it was once commercially published, or your agent has been trying to sell it) ANDIt has been...