Rick Santorum is showing us a classic body language display of contempt in this image. Any unilateral smile is highly suspicious for this very toxic emotion. The "squinting" or partial closure of the former U.S. Senator's right eye is highly congruent with contempt and taken together with his unilateral "one-sided, pseudo-smile"- clinches this emotional diagnosis. Notice that neither of Santorum's lower eyelids have the required concave-up furrow characteristic of all sincere smiles (See Secret # 353: Brad Pitt's Smiling Eyes - Sincere and Insincere Smiles). Note also that the squinting lid and contempt-mouth findings occur on the same side of Santorum's face.
What is most intriguing and a brilliant nonverbal tell here - is that the left side of Rick Santorum's mouth is frowning. The right side of his face is displaying contempt and left side of his face is signalling sadness. This is the proverbial "Twisted Smile". Regardless of your speaking ability, your resume', your platform or your looks - you won't win votes or get people to follow your lead with this facial expression.