In my experience - just using the word "join" usually tells SQL server "inner join", whereas "left join" = LEFT OUTER JOIN.

And while the results might look a little strange at first, it goes to highlight the difference between JOINING criteria, and limiting criteria. In an outer join scenario, the joining criteria aren't going to be limiting on the "side" it's defined on.

Ultimately - something not actually defining the relationship between the two tables should never be in the ON clause.

I do feel your pain if you have a lot of this code out there - could rear its ugly little head just about anywhere.