So true.. and this is a great interviewing technique. I basically ask one question during an interview: what was the hardest problem you ever had to solve? It may sound stupid at first glance, but it gives you insight into not only the breadth of their technical knowledge (since that problem may not be germane to the position you're hiring for), but also the depth of their abilities. The way they answer this question reveals quite a bit about the person. Not only technical, but also their interpersonal abilities.. how they manage their place on a team, how they manage expectations up and below, etc. I can glean quite a bit about the person based on how they answer this one question. Only asking questions about your particular domain doesn't necessarily indicate how good they'll be at solving those types of problems, only how much they happen to know about them. Of course, you can say that perhaps they shouldn't be interviewing for a position they may not be qualified for, but frankly the best people I've ever hired had very little experience in problem sets that were specific to my day-to-day responsibilities, but delving into details about things that they've done told me a great deal about how they solve anything. It may not be the best way to hire, because it requires a breadth of technical knowledge of the interviewer, but it definitely has worked for me. Asking someone to solve a ridiculous puzzle on a whiteboard..when they're obviously nervous about being there in the first place seems kind of dumb to me. However, digging into a problem that they've solved immediately puts them at ease.