It's a great idea and I don't want to appear too critical but:

* Was he only wearing the t-shirt & jeans for one session? Was he sure that was what caused the effect? * $4000 in 7 years? The numbers don't really add up. He was out selling for 2 days a week for 7 years, that should be 700 sessions more or less. He really only made less than $10 a session on average?