Here's a big hint on what I ask on the initial CFI check ride oral.
I have an advantage over FAA inspectors in that I see the weakness on Private and Commercial check rides. These weaknesses can be traced back to the applicants CFI not having a good understand of the subject matter to begin with. If the CFI can't teach it, does the student understand it? Unfortunately not.
What I will do is ask a CFI applicant to teach one or more of these problem areas on the CFI check ride. All of these problems areas align with the CFI PTS. I am hoping that by testing these areas on the CFI check ride we can eliminate the problems on the private and commercial level.