Even if you’re a relatively happy person, you’re bound to run into people who are even more annoyingly happy than you. You know the type — that person who is chipper even before their morning coffee, who makes excessive use of exclamation points, whom bad news just rolls right off.

If you can’t be as happy as those annoyingly happy people, at least you can take solace in one fact: They’re more likely to get ripped off, new research suggests. Researchers at New York University, the University of Chicago and the University of Pennsylvania recently performed a series of studies on the perception of extremely happy people and concluded that they are often assumed to be pushovers.

There is copious research to suggest that appearing happy confers lots of advantages in life, both in personal relationships and in the workplace. Happy people are perceived as more attractive, confident, trustworthy and likeable, past studies show.

But no research has looked at whether very happy people and moderately happy people are treated differently. So the researchers carried out six different studies to determine how the expression of extreme happiness influences how people relate to one another.

The experiments suggest that very happy people are perceived positively in several ways. They were thought to be as likeable as and even warmer than moderately happy people. However, they were also widely considered to be naive.

The researchers used several experiments to explore why this might be. They found that their test subjects assumed, rightly or wrongly, that very happy people maintained their positive outlook either by not processing information deeply, or by sheltering themselves from negative information in the world. And because of these beliefs, people were more likely to try to cheat those who seem very happy, the research showed.

In one experiment, the researchers gave their test subjects a chance to earn money off others by giving them biased advice — a situation somewhat analogous to a used car salesperson earning more commission by persuading a buyer to pay too much for a car. They found that their test subjects gave people who appeared to be very happy significantly more biased advice. In a separate study, they found that their test subjects were more likely to choose very happy people as negotiation partners, because they thought they would be easier to exploit.

There is likely some truth to this stereotype. Past research has shown that emotion can be a powerful tool in negotiation — often, expressions of anger or disappointment can help someone drive a harder bargain than expressions of happiness.

Furthermore, research suggests that people who are in a positive mood are more likely to suppress negative thoughts and pay attention to positive ones instead. Studies have also shown that happiness can make people less critical — for example, encourage them to pay less attention to negative or weak arguments. It’s a belief that also shows up in popular wisdom (“Ignorance is bliss”) and among cynical intellectuals (like French poet Anatole France, who wrote, “A person is never happy except at the price of some ignorance").

The findings have powerful implications, especially for those who engage in negotiations. For example, salespeople in the United States are often taught to be very cheerful, but there’s a risk this could make them seem unprepared, unknowledgeable or less skilled at negotiation, the researchers say. Similarly, political leaders are often encouraged to smile to appear more charismatic, but there’s a risk that excessive displays of happiness could make them seem weak or ineffective.