Sneering often happens as a microexpression, meaning it only briefly flashes quickly across the face before disappearing. It says “this smells fishy.”
During a sneer the buccinator muscles located on the sides of our face contract to draw the corners of the lips sideways toward the ears. This produces a tell-tale dimple in the corners of the mouth and cheeks. This is an expression that usually happens in just seconds and for this reason is honest, so is loaded with meaning. Sneering is similar to eye rolling and is a signal of contempt, disapproval and disrespect the world over. It signals a negative attitude and arrogance to views or persons to which it accompanies.
Sneering says “I don’t care what you think, and I don’t respect you.” Because sneers happen as microexpressions, they often immediately following a stimulus. This makes it very easy to link the negative expression with its cause, serving to read the hidden thoughts.
Couples who sneer when listening to each other indicate that they lack respect and it has been shown that it is a good predictor for breaking up. Sneering can be done by employees who think they know more than their bosses, but whom resist speaking up because of fear of being fired, and by children who lack respect for authority. Wherever sneering shows it’s ugly face, it is due to distain.