I read it in the middle of purchasing a new car in 2010, and had signed paperwork and a purchase agreement to buy car at $X. Next day I'm told "My manager won't let me sell for anything less than $X+Y", after I'd gone through all the trouble of filling out all that paperwork.
Fortunetly I'd just finished a chapter in the book outlining this EXACT sales technique, that relies on a person being more willing to go through with an action if they've committed something to it... like filling out half an hours worth of paperwork. Said no thanks, and found the exact same car an hour away at less than $X.
Haven't underestimated the impact of a salesperson since, and no longer delude myself trying to believe somehow I'm special and immune to such things.