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[Stranger]

Seems that STS oriented people are excellent actors, they can hide pretty well their polarity and real intentions to STO people.

so how can you tell?

That is really funny!

But seriously, I'd say psychopaths are excellent examples of what GW is describing.  They possess superficial charm and a very fluent capacity for deception, as well as a keen understanding of what behavior to produce to extract the desired result from others for their personal benefit (i.e., skill in manipulating others).  As a consequence, unless one is aware of this and trained in such things, it is only when suddenly your life begins to fall apart after encountering such an individual that one realizes that something's not right.