Good brainwashing message: "You want to go to the island." Simple, direct, no real interpretation necessary.
Bad brainwashing message: "You want to be a good consumer." Danger, Will Robinson! You're leaving it up to the subconscious to decide what a 'good consumer' is and how to be one. There ain't no telling what kind of behaviors you're going to get from this one.
And for the love of God, never, ever include metaphor, analogy, or similie in your brainwashing messages! *shudders*
Here ends the public service message of the day.