"You could parachute me down to any place in the world and I will make them a profit" is the kind of claim interviewers should be wary of, says Jeff Simpson, director-psychometrician at Ethos Consulting Group.

People who habitually make such grandiose statements combined with other, often intractable, behaviours may have narcissistic personality traits. Simpson has spent the past six years researching narcissism in the workplace for a PhD and concludes organisations are better off not hiring people with the traits.

He says their performance and productivity tend to fall short of their claims and their inability to integrate socially can affect staff morale.

The Diagnostic and Statistical Manual of Mental Disorders-5 revision group recommends the disorder "be represented and diagnosed by a combination of core impairment in personality functioning and specific pathological personality traits (narcissism, manipulativeness, histrionism, callousness) rather than as a specific type".

The traits can appear as: being self-absorbed and unable to reflect on personal behaviour; a false, inflated self-identity that hides deep insecurity - "I have to be seen this way - or else!" Other signs are: a sense of entitlement, competing with workmates, lack of empathy or ability to see other points of view and intolerance of any form of criticism.

"If you are a parent you'd say - that's a typical 4-year-old or a stroppy teenager," Simpson says. "The key characteristic of narcissism is an incredibly negative reaction to feedback they don't like. It's an adult version of a child's tantrum."

In contrast, more mature high performers with high self-esteem and confidence are likely to be humble, adaptable and open to feedback, motivated by what they don't know.

"If you point something out you don't like they won't kill the messenger." Defensive behaviour such as "narcissistic rage" doesn't appear unless the person is under pressure, Simpson says.

Structured competency-based interviews and role-plays lend themselves to narcissistic predilections for starring in their own drama. He recommends asking questions that probe beyond the catalogue of achievements into areas they are unlikely to have prepared. Questions such as "Why would I not like working with you?" or "Why would I not agree with the solution you proposed?" may elicit an unexpectedly angry response.

Workplace research tends to focus on narcissists as leaders. Simpson studied the impact of narcissism during the early stages of people's career and followed a participant group of 82 commerce graduates.

Using psychiatric and other measures, he found 14 per cent of the group showed evidence of narcissistic traits. Other sources cite between 1 per cent and 16 per cent.

"Within six months of employment, they were the lowest-performing group of our study and they overrated the most as well."

Those who did well after two to three years had no narcissistic characteristics at all but were less impressive at interviews.

Some theories say the roots of narcissism are in childhood where a child was either overindulged by parents, or completely underindulged.

Lacking realistic feedback, some cope by constructing an idealised self-image, becoming obsessed with it, as did Narcissus, in the Greek myth, who died gazing at his reflection in a pool.

While Simpson considers narcissism to be by nature unhealthy - a developmental stage prolonged by social media, self-help books, even school attitudes where "no matter what you do, you are great regardless" - Dr Paul McDonald of Victoria University sees the traits on a continuum.

"Everyone needs a degree of self-love in order to survive. However at a certain point, it becomes pathological and destructive."

He says narcissistic leaders are often dramatic, charismatic and exciting to be around. "They can look you in the eye and tell you about what the future is going to bring without blinking. When they lock on to a socially acceptable positive future they can be very transformational and beneficial to society at large."

But the negatives predominate.

"These are not people who play well with others. They don't plan for succession. They will politically sabotage anyone whom they see as a rival. They can waste corporate money by building an empire, which may not produce value but gives them a high profile in society. They encourage their followers to be sycophants."

Kim Jong Il of North Korea, Robert Mugabe of Zimbabwe, Margaret Thatcher and Donald Trump are frequently cited examples.

"I think it was the politician Adlai Stevenson who said it best: 'Flattery is all right as long as you don't inhale'," McDonald says.

Organisational development consultant Susan Todd has encountered the phenomenon at all levels.

She notes a significant impact on staff morale, performance and productivity.

"Secure, mature people will know what they can and can't do. They keep things in perspective and can work with others," Todd says.

"Narcissists see people and organisations for their own benefit, status and power and are very good at managing up. They might achieve results but you've got to look at the carnage along the way - what they do to people in order to achieve these results."

A chief executive's grandiose "I'm special" attitude permeated one organisation, fostering an attitude that employees and the organisation didn't have to play by the same rules as everyone else.

Good performers and high potentials were not given the opportunity to fully develop on the job.

"There was a culture of fear and blame. People wanted to avoid being made a scapegoat. There was a tendency to hide behind process, to make excuses and blame other people or situations when results weren't delivered or mistakes were made. People weren't prepared to take a risk or do anything that the chief executive would not agree with. People just tended to do what they were told rather than use their initiative."

A lack of trust, reluctance to engage in robust discussion or look at issues from different perspectives meant people were not exposed to ways of working that are conducive to development, growth and high performance.

"This was all contributing to a negative working environment, which was reflected in a low level of staff engagement."

Another case was an interviewee who seemed articulate and engaging and gave excellent examples.

"The interviewers came away saying - she's brilliant, spot on, we need to get her."

Four weeks into the role, her manager found her performance was well below expectations. "There was always an excuse or someone else blamed."

The manager, who was experienced and well regarded, worked intensively with the employee to no avail. Then she had to initiate the harder conversations.

"The person acted as if she was being attacked [canvassed support against her] and started getting quite abusive."

The manager eventually left.

Clusters of persistent behaviours are noticeable over time, Todd says. No amount of resource will bring about change.

"They will never consider they have a problem. If there is an issue, it's always someone else's fault."

Career counsellor Fran Parkin observes that people with narcissistic traits rarely seek out career counselling or employee assistance programmes. However the people they manage do.

"They often have a sense of something not being right, are not able to put their finger on it, and blame themselves. Narcissists tend to attract people who want to please and might be easily swayed."

She suggests that work colleagues be aware of the possibility, without jumping to premature conclusions, to notice the signs and proceed with caution.