I met a wonderful article:
What separates a professional PHP web developer from a scripter?
It is probably the first case where I see a definitive list that can be used to make a formal test and make a rather correct descision based on it - whether the PHP developer is a professional or not.
I consider it much more adequate then those BrainBench tests with questions on some strange topics that a real developer will never meet in practice.
(I got some master sertificates on brainbench in web technologies, think it's a waste of time)