I am often brought in on the hiring process to vet peoples technical skills. I used to just try to ask questions in the hour or two I got with the person, this seemed no better than flipping a coin. Even if the person was honest and we were both talking about the same skill, but how do I know that their experience with that skill is applicable? Now I insist on seeing a portfolio of some kind for coders. A Github, Bitbucket, Sourceforge or any other publicly viewable body of source will do.
15 minutes with someones code is a much better predictor of skill than even several hours of discussion. It costs a lot less too.