I think Aaron Swartz’s explanation of how he hires programmers is pretty applicable to hiring anyone. An excerpt:
There are three questions you have when you’re hiring a programmer (or anyone, for that matter): Are they smart? Can they get stuff done? Can you work with them? Someone who’s smart but doesn’t get stuff done should be your friend, not your employee. You can talk your problems over with them while they procrastinate on their actual job. Someone who gets stuff done but isn’t smart is inefficient: non-smart people get stuff done by doing it the hard way and working with them is slow and frustrating. Someone you can’t work with, you can’t work with.
I think what happens often (at least in the marketing industry) is that people move too far to “can you work with them” side and fail to pay enough attention to the other two buckets.