Well said Steve.
I always have a list of questions that run the whole range. Covering everthing from Logical Scan Density to logical design concepts. I tell every interviewee that I don't expect them to get all the questions (and that I probably couldn't answer them all off the top of my head).
Having to answer tough questions under pressure not only tells you where the candidates knowledge and experience are, but it tends to tell you quite a bit about the person.
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If most people are not willing to see the difficulty, this is mainly because, consciously or unconsciously, they assume that it will be they who will settle these questions for the others, and because they are convinced of their own capacity to do this. -Friedrich August von Hayek
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