I would never rely on a local inspector, no matter which way they went.

Some years ago the Oakland FSDO did a program in which they isnisted that a CFI and a pilot cold not both log PIC on the same flight. A Buffalo FSDO posted on its web site that a student cross country did not count unless all legs were at least 50 NM long. Both public. Both out of the FSDO. Both wrong. Until FAA Legal stepped in, FSDOs accorss the US were going every which way about whether as CFI ride reset the BFR clock. Wrong information on regulatory interpretation, especially Part 61, has always been common.

If you look at the way 61.51 has been official interpreted, a good case could be made for the 3-pilot logging scenario. I don't think that FAA legal has passed on the issue, so we're just speculating.

FWIW, there's one that sounds legit to me: the sole manipulator-safety pilot-CFI scenario where the CFI has no medical.

It's the lack of medical that, to me, makes it legit. The CFI is allowed to teach without a medical, but not act as a safety pilot. So the addiitonal pilot is needed.

As for many of the others, my concern is not that 61.51 will be read more narrowly. It's that the whole set-up might be read as a sham. "The instructor of the instructor of the pilot"? There might be an argument if the instructor of the student was not a CFI-I and the instructor of the instructor was teaching him how to be one, but really....

I think we're getting into the territory of the case where two MEIs flew many flights together to build time and claimed that they instructed each other on every flight. Plenty of legal jargon was tossed around and there were plenty of other things going on in the final NTSB ruling, but IMO the decision that revoked all of their certificates came down to, "that's BS. Nobody believes for a second that these were instructional flights."

http://www.ntsb.gov/O_n_O/docs/AVIATION/4008.PDF