This is a very good question. And to be perfectly honest, I don't know the answer. I don't know if there is an answer.
The problem in my mind is this:
The HUGE majority of the time, members try to be a bit humble, and perhaps downplay their skill, or whatever. "I'm an advanced beginner." "I'm an intermediate."
The problem is this: From my experience, I would say that personally, no reflection on you KoS, having read their other posts in these forums, even when they try to be humble, they are still massively overstating their skill level!
Which is not to say that they can't perform a double lift, or a pass, or whatever.
But I feel that too many magicians haven't begun to comprehend what magic is, beyond a series of tricks performed dealer-demo style. And that makes them a beginner in my book.
So in other words, the problem is this: Magicians tend to rate skills on sleight of hand skill only. In doing so, they vastly overstate skill level, because the majority of magicians ignore the performance theory aspect of magic, and couldn't present to save their lives and don't understand magic at all either.
The problem is compounded when we have a large amount of rubbish flowing out of the production lines. When you ask when something like that is suitable - well, the only thing it teaches is a few weird moves, but nothing more important than that - so we can only rate the product based on the difficulty of its sleights - which is again, bad for the development of a magician.
Brad Henderson once told me, upon asking him for advice, about a particular book: (Brad, if you read this, I hope you don't mind reproducing this sentence; if you do, let me know and I'll remove it immediately) "The perfect beginner's book with lessons no beginner would understand."
And I bought the book, and I saw what he meant.
I look through a book like Psychological Subtleties 2, to use a more recent Mentalist's resource. And it's too easy to say, oh, PS2 just has a whole bunch of tricks. It's so much more than that. Within those tricks are lessons that, if you didn't read carefully enough, you simply wouldn't learn. And it takes some certain knowledge of magic to actually recognise the lessons when you see them. But they're all there. PS2 is an example of a book that shouldn't be rated on sleights or effects "for beginners" or "for intermediates" simply because the lessons are there for everyone.
So if I had to give a general answer, I think skill should be based on understand of magic and ability to perform it. This includes sleight of hand chops of course, but at the same time is much, much more.
