To be certain, SPG brought plenty of subpar properties to the expanded portfolio. No doubt what OP is referring to, though, has more to do with the culture of the rewards program, which I believe most with experience across the two would likely agree that SPG was, well, more rewarding. This extends to the general approach to customer service as well, which in the case of Marriott in recent years I'd be hard-pressed to confer on them anything so lofty as Sears-level status. K-mart, perhaps.