Recruiters often focus on hiring top performers, but little attention is paid to the cost of managing those who, once hired, create a toxic workplace.

Problem employees come at a high cost. They can destroy morale, lower ethical standards, contribute to a toxic workplace culture and bring the organisation into disrepute. There might even be protracted legal involvement as well as regulatory liabilities.

A recent large study by Dylan Minor, at the Harvard School of Business, and Michael Housman, an analyst at Cornerstone OnDemand, concludes that avoiding hiring a toxic worker in the first place enhances company performance to a much greater extent than replacing an average worker with a star performer.

So there are good reasons to weed out problem candidates in the interview process before they can do damage. Here are six strategies to help human resources professionals avoid a toxic workplace.

1. Use behavioural interviewing techniques.

They have been shown to be better predictors of on-the-job performance. Ask candidates how they handled situations in the past rather than giving imaginary scenarios.

Consider using questions such as:

• Tell me about a time when you had a conflict at work. What happened?
• Can you give me an example of a time when you failed? What did you learn from the experience?
• Tell me about a time when you found it difficult to work with someone. How did you handle it?
• What are some signals that you are under too much stress?
• What about yourself would you like to improve the most? And a second thing? And a third?
• When have you failed? What happened and what did you learn from the experience?
• What would your former employer say about you – positive and negative?

2. Observe and listen closely to the candidate’s responses.

Look for a tendency to blame or speak negatively about others. Does he or she take responsibility for outcomes, or is someone else always to blame?

3. Follow up on references carefully.

Phone calls can be better than emails because you can interpret responses and ask follow-up questions. Listen for any hesitation or nuance that might suggest something negative. Questions such as, “What is this person like to work with?”, “Would you hire them again?”, or “Where could they improve?” can help to uncover any problems that the referee might hesitate to mention at first.

4. Go further than provided references.

Use your network to call people who might know the candidate and get their input: former colleagues, officials in community organisations, professors or board members.

5. Talk to receptionists and drivers who might have encountered the candidate.

It’s usually a bad sign if candidates treat staff members badly. Zappos, the US internet shoe store, asks the drivers who bring candidates from the airport to its Las Vegas headquarters how the candidate spoke to them. If the driver was not treated well, the person is not hired.

6. Have the interviewing team have a meal with the candidate.

This will give a better picture of how the person handles themselves outside an interview situation, and can be quite revealing. Look for flexibility, civility and how the person interacts with others generally.

Talent and skills can’t make up for the cost to the organisation of hiring toxic employees. Weed them out before they join the team.