I confess that I find the note by Lutz Albers much more comprehensible than the article about outer joins itself. I have found that doing everything inside of a stored procedure that begins like this ALWAYS solves these kinds of problems:

SET QUOTED_IDENTIFIER ON

GO

SET ANSI_NULLS ON

GO

The reason it works? Because setting ANSI NULLS ON gets rid of the three-way logic (true, false, and null). I have read numerous articles telling me that setting ANSI NULLS ON is totaly wrong. To this, I respectfully disagree: I program in the real world and don't have time for debates about set theory logic. Turning them off gets rid of these mysterious problems and that's good enough for me.