[Physkal]

I wonder how effective is this strategy, and is there a name for it? Reminds me of people planting 20 dollar bills in their auto seats before a oil change/car repair. If the money is missing, what does that actually say about quality of the car repair? Also doesn't trust go both ways and you risk damaging the relationship with the vrndor? I'd be very reluctant to repair someone's car again or who plant judgmental traps.

[tomrod]

There is an academic literature in game theory dealing with this topic, the key text is called "Repeated Games and Reputation." The difference from your example and the OP is that OP's experience isn't a repeated purchase (to my understanding). For Van Halen and brown M&Ms, there are elements of leverage in negotiation and other elements of reputation.