Bian Xiao likes it once in my hand. Give it a bite. What's the joke?

In the Chinese class, the teacher is giving a big talk.

Teacher: "Students, please remember that anyone who is truly moral will not accuse others of their shortcomings."

A school scum stood up and said sternly to the teacher, "teacher, it's not all like this." My brother blames other people's shortcomings every day and makes money from them, but no one has ever said that he is immoral. "

He was a little angry when the teacher saw that the students opposed his opinion. He asked angrily, "What does your brother do?"

Dongdong: "proofreading by publishing house."