"Imagine overhearing a conversation in which a salesperson profusely compliments a nearby customer on the elegance of her outfit," write authors Elaine Chan (Tilburg University) and Jaideep Sengupta (Hong Kong University of Science and Technology). The customer has already paid for her purchase, and she looks elegant to you, so you assume the compliment is sincere.

The authors conducted four experiments in clothing stores to investigate consumers' reactions to salespeople's flattery. In each case, participants heard salespeople making flattering comments about other customers' sense of style. Then researchers asked various questions about their opinions of the salespeople. The authors focused on flattery that could be judged sincere, although they also examined reactions to flattery that observers would judge insincere, like when a salesperson offers profuse compliments before a customer makes a purchase.

"We found robust evidence that observers form both positive and negative reactions towards a purveyor of sincere flattery," the authors write. When participants had time to form thoughtful, deliberate responses they tended to have positive opinions of the flatterers. But gut reactions to flattery were far more negative. "These implicit reactions towards seemingly sincere flattery are as negative as when the observer has good reason to believe that flattery is actually insincere," the authors write.

The authors found that observing someone else being flattered causes people to compare themselves to that person, which leads to feelings of envy. Another experiment showed that participants experienced more envy when the target of flattery was a peer (a student at the same university).

The authors also found that consumers were motivated by envy to choose an expensive, stylish pair of jeans over a cheaper standard pair. "Over time, envy-based hostility towards the salesperson is no longer a part of the purchase decision; instead, this decision is influenced primarily by the wish to reduce envy -- by appearing stylish oneself," the authors conclude.