A Man`s Worth Cannot Be Measured by His Looks

A few days ago, I saw one of my classmates cheating on the accounting exam. I was so surprised that she did such a thing. It made me feel sad and confused. Why did she cheat? Maybe she just wanted to get higher grades and didn't want to lose face. But at any rate, cheating is a vile action. 　
I told one of my friends about our classmate's cheating, and she found it hard to believe. Even though the girl has a good temperament, our impression of her has changed. 　
Now, I no longer trust people based on their looks. Maybe someone looks honest, but he or she has bad intentions. Can we tell by looks alone? So, I've lost faith in society