According to Dr. Stephen Diamond, a clinical and forensic psychologist writing for Psychology Today, bitter, jaded people tend to project a self-righteous attitude suggesting they're justified in feeling resentment. They're often bored and cynical. They observe and criticize more often than they participate. Because they believe they've been burned, they no longer have the trust necessary to build solid, positive relationships. They believe the world is unfair and freely express their impatience and anger. They no longer expect success, but don't accept responsibility for their failures; instead, they blame others. They're almost always irritable and frequently express annoyance in most situations.

People who are bitter and jaded may lash out at others, cruelly using sarcasm and criticism. They are often angry, unhappy people who feel they are victims. According to psychologist Carsten Wrosch, cited in an article for "The Atlantic," people who believe others are at fault for their problems or failures often express bitterness or anger rather than sadness or regret. This negativity can also take it's toll on the person's physical health. Science writer Elizabeth Svoboda reports in Psychology Today that research shows that bitterness can lead to increased smoking, drinking and even suicide, and that it's also been linked to increased rates of heart disease.

In his Psychology Today article, Diamond suggests that jaded, bitter people never learned appropriate ways to manage the inevitable disappointments of life. A genetic predisposition toward bitterness has not yet been demonstrated by research, according to Svoboda, but it is clear that some people are unable to respond in a healthy way to situations they believe to be unfair and so they become resentful.

It can be toxic to have bitter, jaded people in your life. The cynicism jaded people project can bring down the spirits of all around them. While enthusiasm and optimism can be contagious, so can pessimism and apathy. Having even one bitter employee can poison your work environment. If your boss or co-worker is always negative and critical, it's difficult to maintain a positive outlook. Creative ideas you present are likely to be criticized. Having an embittered partner is even more challenging. Living with the daily abuse of ridicule will take a toll on your emotional well-being, says clinical psychologist George Simon. Professional help may be necessary to help the person work through the issues behind the bitterness.