A lot of people here say this, and no doubt it is indeed a real problem. Yet none of the books I've read on negotiation ever suggested something as inane as the orange juice test. They all have sections or a chapter on "OK, now that you've got the deal, how are you going to ensure the counterpart follows through?"
The solution will depend on the situation. Some of it is your responsibility for monitoring. Some of it (probably a lot, actually) is putting penalties in the contract. Some of it is being proactive and exploring what constraints the other person may be under (Is he under-resourced? Are there other decision makers than him who can screw it up? Can he outline a plan so you can see potential flaws?).
But nowhere do they suggest playing opaque games.