Throughout the play numerous details emerge about Biff that show his lack of moral fiber and personal integrity, beginning at an early age.
- As a boy, Biff stole lumber from a construction site with his father's encouragement.
- In high school he was too lazy to study, choosing instead to cheat on his tests by getting answer from his friend Bernard. Eventually he fails math and does not graduate from high school.
- In high school he deceived his coach and stole a football from the locker room.
- Also in high school, Biff entertained the other students in math class by making fun of the teacher; Biff was crossing his eyes and speaking with a lisp when Mr. Birnbaum walked into the room.
- As a adult, Biff stole a suit in Kansas City and spent three months in jail.
- On another occasion, he stole Bill Oliver's expensive fountain pen after visiting the man's office to seek a job.
- Toward the end of the drama, Biff abandons Willy, who is very ill, at the restaurant where they were to have dinner.
At the play's conclusion, Biff faces the truth about himself and the life he has led, but the prospects of his changing do not seem favorable.