Mitt Romney displays here a classical body language example of the Asymmetrical "Smile". Moreover, not only is his left side not smiling, it is frowning. Neither is the right-side of his mouth for that matter. This is a "Pseudo-Smile". In addition, the Presidential candidate's lips are thinned - indicating a component of anger component. Along with his left-sided frown side - these nonverbals reflect Mitt's true emotional tone.
We all make this expression from time to time (and variations of it), and more than we realized. But when you're running for President, you need to extricate this expression from your routine. Mr. Romney uses this facial expression far too much and in the context of verbal disparity. Said another way, his words are positive, but his expressions (this and others) are negative. When the verbal and nonverbal messages are contradictory - it sends feelings of cognitive and emotional dissonance to audiences and the public at large. It also indicates the former Massachusetts Governor is truly feeling such dueling emotions. To the public, this makes him "feel" more like a politician - and less like the guy next door which he should be - in truth and in projection. If Mitt Romney wants to become President, he must solve this problem. The same is true for you - even is your subjects are more mundane and for much smaller audiences.
Analysis # 1139: How Not to Build Rapport
Analysis # 1003: Obama's Dropped Jaw False Smile
Analysis # 1009: A Sure Sign of a False Smile
Analysis # 1553: Ann & Mitt Romney's Body Language at NRA Meeting
Analysis # 1915: Mitt Romney's Response to Supreme Court's Decision on "Obamacare"
Analysis # 1863: Sharapova's Lips of Anger
Analysis # 531: Sarkozy's Mouth Tells Us What He's Thinking