Happy Birthday, Laga!
I've been thinking about it, and I have to say the idea of an interview coach is a very good one. I mean, I thought I was being friendly and outgoing, you know? And for me, it was. But I failed to project. I learned to put down my pen, take my hands all the way off the keyboard, not just hover in place waiting for the interruption to finish blahblahblah and let me get on with work. I learned to swivel my chair and focus totally on the speaker, smile till I felt like a kabuki mask. I practiced in the mirror, smiling so that the outside ends of my eyebrows came down a bit, my eye corners crinkled--evidently those are "tells" of a "real smile", and you can teach them to your facial muscles.
The problem seemed to be that while I was perfectly approachable and friendly and chatty on the inside, on the outside I was perceived like Agent Cho. So although it felt extremely fake, I called on my acting background, gritted my teeth, and performed. Yes, it cut my job efficiency, by a significant amount. But the people I worked for and with felt a lot more comfortable around me, and my performance evals actually improved. It was frustrating for me, because I could accomplish more if I was allowed to focus on task. But apparently when I did that I made everyone else uncomfortable.