The guy sounds like a genius, it's pretty straightforward Sun Tzu, or anyone of a number of tacticians who have discovered the same thing, when your hand is weak present it as strong, when your hand is strong present it as weak.
Usually, though, you don't know. And most people don't follow it, so you kind of have to assume any random person doesn't until you have better information. Hopefully this is before he beats you.
Right in his case, he exposed it when he needed to, and that was on rare occasion. The funny part is that you would be surprised how much of superiority is engrained by behavior, people would underestimate him more than one time which really surprised me, it was like his actions where able to turn off instinctual safeguards, so even when someone logically knew he was sandbagging, they would still get all the cues that, they had the upper hand. He would trap people with habitual and natural interaction with him, you may go a year with him playing dumb (simple is a better word for it) and you get lulled into the routine off it, then when needed he became shrewd. With people that he was not in an adversarial relationship with, he just assumed the manner as his default manner. So it was not totally manipulative. As he said, he is a simple guy and likes to use the simple part of his brain, but can draw on the rest when needed. In a way, it was not fake, hence my not being able to detect it. I am usually very good at detecting people that are putting up fronts.
It was not that simple, this guy knew how to use behaviors and social norms against adversarial individuals. To the extent that he was able to use human nature and unspoken language of both his, theirs and others against the person. Coupled with, planning out steps far in advance and setting up multistage scenarios in which each piece was part of a grand plan that had to fall into place just right, made him formidable when negotiating.
I think his point was that, not knowing the strategy gives the strategist an advantage and the adversary a disadvantage. Once used the adversary is the wiser for the experience.
Unfortunately we on HN do not like generalization and the poster used anyone, in which he probably meant a good deal or a majority. I would note though, that anyone that is able to fundamentally change their character, to not exude intelligence, is probably not a one trick pony. He was the only experience with a person that cunning, but to me it seems like his character would be a prerequisite.
