Don’t be deceived by looks
That doesn’t mean you consider everyone who looks nice as a potential evil doer. What you need to do is to never make looks the criteria to consider anyone good for you. You need to exercise right judgement such as checking for facts, understanding the mentality of the person and his/her reasoning. Obviously, unlike looks the things for right judgement may need more patience. By someone’s look you may get into the error of thinking they are very pleasant people to deal with. However, when you ask them to help you, then you will come to know their true nature. No wonder, you need to never depend on looks alone.
Do not judge by appearances, but judge with right judgment. (John 7:24)
When they came, he looked on Eliab and thought, “Surely the Lord’s anointed is before him.” But the Lord said to Samuel, “Do not look on his appearance or on the height of his stature, because I have rejected him. For the Lord sees not as man sees: man looks on the outward appearance, but the Lord looks on the heart.” (1 Samuel 16: 6-7) (this happened when Samuel was searching for someone to anoint Saul’s replacement as the King of Israel)