The piece nobody has written yet, because they'd need to have read The Tao of Spycraft and the vault's behavioral-elicitation corpus (Hughes' Six-Minute X-Ray, the elicitation framework, Greene) in the same week, is this:
That the 2,500-year-old Chinese "knowing men" tradition and modern behavioral elicitation are the same craft wearing different clothes — both are engines for reading a person's interior off their exterior, both work by managing the target's desires rather than extracting his secrets, and both quietly carry the same confession in their fine print: the reader is the most exploitable person in the room. The essay would run the ancient and the modern side by side — Li K'o's five criteria next to a rapport-based elicitation script, the cloud-ch'i prognosticator next to the body-language "expert" — and argue that every advance in reading-people is simultaneously an advance in the techniques available to deceive the reader, so the field can never get ahead of itself. The title writes itself: the spy is a mirror, and the better he reads you, the more precisely you can show him what he expects to see.
Links: Knowing Men as Epistemological Project, Turned Agent vs. Western Double Agent, The Analyst Is the Easiest Target.