Nancy Puccinelli of Oxford University's Saïd Business School confirms what anybody who has been to a mall in the past ten years can tell you: excessive decorations, intrusive music, and "enforced holiday cheer" are obnoxious and grating. She says, "We know from studies of consumer behavior that moderation in festive decor leads consumers to spend more and to like the retailer more." Also,

The earlier the decorations go up, the sooner the stress begins and the greater it will be once the holidays arrive. As a result, shoppers will find the festive Christmas decorations that much more aversive. There is some evidence that early in the morning consumers might be more open to new things, which might make them somewhat less turned off by festive décor. But most of the time, over-the-top Christmas decorations are just off-putting.