>Makes them really hard to interview because they are so good at interviewing!

Hmm. In my experience interviewing Oxbridge grads, I didn't find that. Being good at talking around gaps in knowledge works very well in free flowing conversations, but if an interviewer ask a specific question, and the interviewee cannot answer it, then the ability to talk round it does no good. E.g. I used to ask a question relating to the amortization of a loan, and I would ask the interviewee to draw a graph of time vs. loan balance. You can't talk your way out of not being able to do that.