Don't Trust Everything You See Even Salt Looks Like Sugar
Don't trust everything you see, even salt looks like sugar but if you make this mistake you will quickly realize your error once you take a taste. Sometimes things may look similar but they can actually be very different underneath. Your eyes can deceive you, and just because it looks like something familiar the truth could be far different. People are the same way. Serial killers through history have generally appeared to be law abiding people and individuals who you would want to be friends with. If these monsters showed what they were truly like on the outside then they would not be able to find victims, instead they seem like nice normal people until they get their prey alone and then things change quickly.
Seeing and believing are not always the same thing. It is important to judge people and things for who or what they truly are, not based on how they look. Your eyes will help you get an initial impression but this is not enough on its own, you also have to determine what someone or something is like on the inside as well. Some people make the mistake of refusing to believe that their eyes could be wrong and they take everything at face value, often ending up a victim as a result. Verify what your eyes tell you before you form a concrete belief about someone or something so that you do not end up making a huge mistake.