Anyone I ever interviewed for a job position over the years usually had done their homework and although nervous, so to speak, had quite alot of industry or job knowledge. I do however use the technique you mentioned in your last sentence when extracting information from the wife after she has been shopping,lol, I pretend I have no idea where she has been or what she has spent, and ask basic questions to look for nervousness, thus ensuring I remember to check the credit card statements.lol