I am far more impressed with someone who slightly understates their abilities and accomplishments than someone who even slightly overstates them.
As a student, you can get away with this a bit. You might get found out, but it's ok to ask for instruction. Interviewing for a faculty position though.. well, that's different. You are presenting yourself as an expert, and the work you present defines that area of expertise. My observations on several recent searches indicate you will get discovered. Damn, it looks embarrassing. Overconfidence will work in your favour.. to a point. And stepping outside your comfort zone is important, but be ready to acknowledge where you are stretching yourself and know where your true wheelhouse is. I was pretty brash when I interviewed, but I'm also pretty sure I said "I don't know" at least once and I don't recall anyone pointing out any logical or factual flaws in what I presented.
So here's the second kicker.. of recent such search-related events, more male candidates than female candidates have gotten caught in this trap. Now, these are still small number statistics, and they're not 100% even at that. But it is a curious observation, and I will keep collecting data. In the case where people started digging into the female candidates' knowledge (something I also noticed happens more often.. but that's a different story), they more often than not revealed the depth of their knowledge and ability to communicate it. Apparently they were holding this on reserve, or were sparing us those "I'm saying this so you know that I know" moments. Male candidates were more likely to get tripped up as the questions started to flow.. usually because they had left an obvious thread to tug at.
What are your thoughts on interview strategy? Present yourself as all-knowing regardless of your experience? Present yourself as close to "you" as you can under such artificial circumstances? Does anyone else have observations on gender differences? Does a preference here one way or the other here represent an unconscious bias in some way? And am I swimming against the tide by going for the understated? What should I tell my trainees when they go out to interview?