Sorry, let me clarify. I am defining a bad interview in which the interviewer did not meet the requirements of the interview, or did not represent MIT. Not merely an interview that did not seem to sparkle. I had one about 8 years ago which was like pulling teeth (and I am heavily paraphrasing below):
Me: So what sorts of things do you enjoy?
Candidate: Oh…[very long pause]… stuff
Me: OK, Stuff is good. Can you give me a for instance. What is any one thing that you really enjoy?
Candidate: Hmmmm… [even longer pause] I like reading.
Me: [Getting slightly desperate] Reading is good. I also like reading. So what do you most enjoy reading? Fiction? Biography? Epic Poetry? Physics Textbooks? What?
Candidate: Oh a whole bunch of stuff…
This interview did not sparkle. The interview report was very hard to write. I am not sure that either of us had wild and crazy fun, but it was not a inappropriate interview. I was not detached, neither of us failed to show, both the interviewer and the interviewee were fully present physically and mentally at the interview. The conversation was broadly cheerful and I did my darnest to be supportive without mis-setting any expectations.
You ask how I as an RC feel that I have a view of what is going on in my region at hundreds of interviews that I do not attend. MIT grades each of the interview reports we write. On those occasions when an interviewer, usually a new EC, gets poor scores, the regional chairs tend to step in fairly quickly. And the poor scores are often an interviewer who does not really get the role of the MIT interview (often they are people who interview a lot at work, and wrongly think that the MIT interview would work the same way). I also talk to the ECs in my region quite a bit. I fairly quickly find out when I need to do something. @JustOneDad says that I need some notification of how every interview went, or I cannot meaningfully stand behind my 1% figures. I can tell you that I do get some (albeit limited) visibility of every interview in my region, and I do stand by my claims earlier.