For once or twice in its lifetime, points.com offered good exchange rates in Dec. 2012 from Priority Club to Amtrak & from Amtrak to Asia Miles. So good in fact that several of us grabbed the bargain, only to see points.com reverse/ rescind the exchanges, claiming that they had made a "mistake."
That's a reason to call points.com a scam: If a customer makes a mistake or finds out that the rate is unfair, the transaction is "irreversible." But if points.com has second thoughts about the rate, it is reversible!