When you look at the strangers face while dreaming, then such dream shows various aspects of your personality. The different faces have different meanings. The funny face may be a suggestion to be more relaxed. The face without the nose eyes or mouth, shows that you are feeling numb and even have no opinions about something, or simply feel uninteresting person. The happy face with the smile on it, signifies your inner joy, where you feel happy even about minor things. If you look at the mirror at your own face, then you have to deal with some situation you were delaying. You are telling it for yourself during the sleep. The ugly faces, or the ones that are out of proportion, shows your fears.
Read more about dreaming of Faces in other dream meanings interpretations.