One profoundly valuable body language skill is the ability to detect insincerity. The single most common nonverbal signal of insincerity is over frequently contracting the forehead muscles. The correlation is even higher when it's limited to central forehead contraction (CFC) - as opposed to the entire width of the forehead. Moreover, if there's any inkling of a coexisting "mouth smile" (insincere) with the central forehead contraction - a huge red flag is raised.
We all make this expression from time to time when we're feeling:
1. Arrogant (although this is of course, not the only expression of arrogance)
2. Contempt (there are also other expressions for contempt)
As human beings, we're expected to feel such feelings occasionally. Yet when a person exhibits the CFC with a smile chronically - be warned.
Pundits, bad actors/actresses, most news reporters/anchors make this expression with a higher frequency compared with the general population. Politicians also display this nonverbal facial cluster much more than average. Of all the candidates, from all the parties running for the presidency this election cycle, no one displays this facial expression more than Ted Cruz.
CFC + partial mouth pseudo-smile during 0:33 and just after Mr. Cruz is referencing Megyn Kelly and Donald Trump: "If she asks him mean question - I mean his hair might stand on-end."
This CFC with partial/insincere mouth smile is seen just after Sen. Cruz challenged Mr. Trump to a one-on-one debate (during 0:50).
Nonverbal Communication Analysis No. 3447: Chris Pine, "The Finest Hours" and Body Language
Nonverbal Communication Analysis No. 3325: Vladimir Putin, the United Nations, Russian Soil and Confidence Levels
Nonverbal Communication Analysis No. 3272: Donald Trump, Megyn Kelly, Deception and Misogyny
Nonverbal Communication Analysis No. 3328: PewDiePie on Stephen Colbert's Late Show - a Common Body Language Alpha Up-Regulator
Nonverbal Communication Analysis No. 3267: Jeb Bush and Emotional Dissonance
Nonverbal Communication Analysis No. 3287: Hillary Clinton, Email Servers and Crisis Management
Nonverbal Communication Analysis No. 3310: Carly Fiorina's response to Donald Trump's, "Look at that Face!"