Have you heard of Neuro-Linguistic Programing (NLP)? It was big in the 70's. I was in the Army active reserve in the late 70's and we spent 6 full days (3 weekends) studying NLP. Apparently, at that time the Army used these techniques to train their competitive 45 cal. pistol team. The part that pertained to my unit was the 'reading' of body language and eye movements when questioning a person. (I was in a Counter Intelligence unit; we were not integrators officially, but we did run several types of investigations.) Anyway, the Army was so impressed with it that they spent 6 full days teaching it to us. I have since forgot most of it and have long since thrown away all the handouts that we were given. I do remember that if we asked someone a question and their eyes looked up and to the left, they were accessing their memories; if they looked down and to the left, they were using their imagination (lying). I don't know if the Army still thinks it a good tool to use or not. Here is an article dealing with the subject:
https://en.wikipedia.org/wiki/Neuro-linguistic_programming
But now that you spilled the beans and let out all the secrets, scam artists will be looking up and to the left, to make you think they are thinking, and never looking down and to the left when they are lying, which leaves you back where you were when you started. But I still think there are non verbal ques that are unscripted that we pick up on. How they affect the relationship is probably important, but probably no more predictable of the actual value of the relationship itself. Codependents still find their partners, and con artists still find their marks, and it's a combination of a lot of faulty sensory experiences. I have picked up a lot of ques in my life, which often proved to be embarrassingly inaccurate. Or did I pick up the cues just fine, but fumble in my responses. Who knows? Communication is a mess. Maybe in a perfect world we would all be high functioning autistics who said only what they meant, and understood only what was said.