Venezuela's President Hugo Chavez is an easy target. This is a common expression for him. He is feeling disgust (mild to moderate) towards someone or something and he's trying to eek out a smile, but his smile is falling far short. Some classic components of disgust seen here are dilated nostrils and the tightening around his mouth - particularly in the "mustache area", prominent nasal-labial folds, and a protruding lower lip, and subtle wrinkling on the bridge of his nose. As the disgust intensifies, these characteristics grow more prominent, particularly findings in and around the nose.
Notice also, Hugo's raised right eyebrow - this is a signal of doubt as is often referred to as the "Skeptics Eyebrow". Mr. Chavez doubts something he sees and he is trying to look amused by smiling, while his true emotions of disgust and skepticism leak through.
Be very aware of the subtle, the camouflaged and the ruse. Those who intend to deceive, harm and take advantage of others rarely come dressed in a cloak and twisting their mustaches. When negative emotions are layered with positive emotions, most people miss the negative ones. Every day is a masquerade.