Do most dogs treat people based on their physical apparence?

Well, most of the time, it's not the physical appearance (or beauty) that the dog judges. Most dogs who haven't been socialized (or who have not met that many humans during its puppy years) will base its approach depending on how dogs instinctively meet each other. Approaching them full frontal with your chest up straight while looking into their eyes can signify that you're dominant or trying to dominate. Not looking at them straight in the eyes and approaching them sideways can be perceived as being friendly. Hunching and averting one's gaze can lead them take the chance to take over.

We always hear Cesar Milan saying that people need to be calm and assertive. He also mentions that you have to relax and walk with confidence. Confidence can also attribute to how a dog can judge you.