It sounds plausible, but I think its something of a premature conclusion. Consider how one would best fake an emotion: simply by motivating oneself to feel that way. Faking an expression is much much harder than simply choosing a field that matches your own moods and preferences. The reason we see people who don't appear genuine in high ranking positions as well as very low ones is that they are motivated by something other than the above, a drive for excellence or desperation where feelings do become a tool, but thinking in terms of the majority its easier to assume convention and self-discipline makes most peoples professionalism indistinguishable from any other motivator they might feel.