IndustryGamers - Facebook Games from Zynga Are 'Parasitic.' By Alex St. John.
It is fair to say that with Facebook moving aggressively to contain the leak by preventing games from freely spamming their users that the halcyon days of “Social Gaming” (part 1) are nearly at an end, and the online game market will return to business as usual in which great, genuinely “social” games spread virally online without needing help from anybody and lesser titles will rely on buying advertising and doing distribution deals to reach their audiences. Even Zynga, having nearly outgrown its host organism will have to wean itself from dependence on Facebook and learn how to make games that people genuinely want to play and share with their friends voluntarily.

Gamasutra - The Psychology Of Games: The Glitcher's Dilemma. Thanks Joker961.
So what do you do? Psychologists and economists who study this kind of decision-making call it a "social dilemma." In these situations each person has what's called a "dominating" alternative where they're most likely to win (in this example, abusing the glitch) but most people REALLY want the "nondominating" alternative produced when everyone chooses to cooperate. Especially once the novelty factor wears off.