Your user profile states that you are an attending. Are you sure??
In other words, if you are an attending, aren't you past the phase of phear of the unknown slide? 😎
I don't think the phenomenon of showing unknown slides to interviewees can necessarily be trended by subspecialty, or even level of training. It seems like if an attending happens to be in the process of signing out a frozen or a cool case while you are interviewing with them, you might get shown the case, or asked a question about it, and not necessarily in "pimp" fashion either.
I personally think it's a neat interaction to have, on several levels:
(1) you get a chance to see a case you might never have seen before
(2) you get to evaluate the nature of their daily service/consult material, which is important for fellowships
(3) you get to demonstrate your (usually) organized approach to, and your diagnostic acumen on a case
(4) the interviewer gets to see how well you perform socially as well as diagnostically, under situations that some might consider high-stress
(5) it's the closest to a "real-life" interaction that you will have with an attending on your interview day.
On a couple of interviews I was shown slides and I was pretty sure of the diagnosis so I volunteered the answer. I was right one time and somewhat right the second. But improving your diagnostic skills is what fellowship is for, so I don't see any downside at all.