If the position is a technical post, it will be best for interviewers to ask technical questions, not limited to the post requirements. In this way he can filter the con man's.
If the position is half technical half sales, is best to test both technical and interpersonal skills.
I once attended a pre sales technical consultant post and when the engineer interviewed me, he was fully impressed as I managed to provide more info than his expectations. But I know my standings and didn't want to exceed his knowledge or else it will backfire.
He offered me the job on the spot without a 2nd thought.
But I didn't accepted it after a failed salary negotiation with the stingy hr.