Appearances are deceptive.
Everybody wears a mask in different occasions. People project a certain image to show the public as to cover their true selves.
For example, you suffer a heartbreak and because you don't want to be pitied by your friends, you act happy and unaffected by the recent turmoil in your life. Your friends will see that you are okay and be satisfied with what you have projected. They are deceived by your outward appearance. Thus, appearances are deceptive.
Another example is a person who seems to be very wealthy. He or she wears branded clothes, dines in famous and pricey restaurants, stays in 5-star hotels, all these luxuries are paid for by his or her benefactor. Said person is not really wealthy, he or she just looks like it.