The friend we've confided in, we learn, has been passing our confidences along as bits of juicy gossip to others.
Then there's the trusting spouse who makes career sacrifices – then finds out his "other half" has been cheating and has lined up his replacement.
Even if it's as simple as being taken by a smarmy salesman, these situations can often bring a sense of bitter shame mixed in with the anger.
Why Bad Things Happen to Good People
What's wrong with us? Or the victims we know? Is there truly a sucker born every minute, as circus promoter P.T. Barnum is widely credited with saying?
Not necessarily, says Lou Manza, PhD, chairperson of psychology at Lebanon Valley College in Annville, Pa. "I don't think people are innately clueless, but emotions factor into it and our brains get distracted."
"Knowledge is power, and ignorance is not bliss," says Yvonne Thomas, PhD, a Los Angeles-based psychologist.
"People may not want to face the truth … but in the end, it will hurt them a lot worse," she says. "You don't want to be in fairytale lalaland, because the consequences will be that much more traumatic."
Don't Be a Sucker
While there are downsides to being too cynical, many of us do need to boost our inner skeptic to avoid being blindsided. Here's how:
Approach it like a scientist. "In science, if a certain theory is dominant, we don't doubt it because we have data backing it up. But if we come across other information that is convincing, it can make us look in other directions," says Manza.
"If there is no evidence to suggest something is awry, leave it alone; but when there is evidence, you need to act more rationally and try to put your emotions aside," he says. "Try to be as objective as possible. The more subjective you get, the more errors you can make."