I feel the same way. Obviously I can't measure false negatives, because they don't get hired, but I can't remember having been duped before. My process is to ask them to describe their role on some projects on their resume and then keep asking them deeper and deeper questions about it until one of us hits the limit of our knowledge. I only ever ask people questions about things they claim to have done. This probably creates some false negatives with really shy people, but it's easy to suss out the bull shitters.