This excerpt from the Democratic presidential candidates' debate held on June 3rd, 2007. The excerpt shows Hillary Clinton and Barack Obama's responses after John Edwards has sharply criticized them for not being more outspoken against the war in Iraq on the floor of the Senate.
As you can see here, Hillary Clinton started with a full, social smile, seeking to negate Edwards' attack. Very soon after the smile starts fading. The way the smile turns into a grimace as it fades betrays the extent to which it was not a true smile to begin with.
At the same time, Barack Obama showed some anger and dismissal. Obama turns his head away from Edwards and his lips appear to tighten together in a slight sign of frustration with Edwards' attack.
This excerpt from the Republican presidential candidates debate held on June 5th, 2007. the excerpt shows Rudolph Giuliani's reaction after being read a quote in which a Rhode Island priest has compared Giuliani's position on abortion to Pontius Pilate's personal opposition to the crucifixion Jesus Christ but allowing him to die anyway.
First, note that the normal resting position of Giuliani's mouth is in the form of a disgust reaction with the corners of the mouth turned down (top photo). In the middle of this question, he shows a look of frustration (2nd photo). The 3rd photo shows very intense anger with the lips pressed firmly together while looking down shows signs of sadness. Giuliani finally settles on a smile toward the end of the question (bottom photo).