Maybe the trickiest part of the job-search process is finding appropriate references. You’ve probably heard the saying “you should never ask a question you don’t know the answer to.” When it comes to job references, you can twist that a bit to say “never let one of your references be used unless you are sure of what he or she is going to say.”

That is increasingly important, according to a new survey of 1,000 senior managers by OfficeTeam, an administrative staffing service. OfficeTeam reports that more than 20 percent of job candidates are disqualified from the hiring process during reference checks. That’s not just 20 percent of people looking for work, but 20 percent of the people who presumably have passed the scrutiny of résumé review and job interviews. That’s one in five people the company is very serious about hiring. So what goes wrong?

OfficeTeam says that 36 percent of hiring agents want a description of past job duties and experience; 30 percent seek information about the job candidate’s strengths and weaknesses; 11 percent seek to simply confirm job title and dates of employment; 8 percent want descriptions of the job candidate’s work accomplishments; 7 percent want to find out how the candidate handles various work cultures. The remaining 7 percent are unclear about why they are calling.

I once had a friend who was looking for work for nearly a year. We had been colleagues for only two years, but he apparently felt that we had worked together closely enough that I would be a good reference. My friend was a really bright, incisive individual with great research and writing skills. But he also had a flaw.

What my friend failed to understand is that I witnessed numerous instances of emotional outbursts against coworkers and the public during the time we worked together. He was a very good employee until he crossed that line and began berating the people around him. It was very unprofessional behavior.

One day, I got a call from an employer saying that this individual had listed me as a reference. He had not asked me to be a reference, but simply put my name and phone number down on a job application. The interviewer asked me various things about my friend’s work habits. I answered that his skills were impeccable and that he was able to produce quality work on a continuing basis. We talked for maybe ten minutes and then the interviewer asked if there was anything else I thought he should know.

I gulped. I wanted to help my friend, but I didn’t want to mislead the interviewer. I finally said that he had been known to lose his temper at times, which was embarrassing to all of those around him.

“That’s not the first time I’ve heard that,” the interviewer told me. I was relieved a bit, and told the interviewer that perhaps he had matured and the problem was in the past.

My friend got the job, but lost it about six months later when he had an emotional outburst that targeted a coworker.

I still wonder whether I should have shared that much information about him. I’ve come to the conclusion that I presented an accurate and balanced picture of my former coworker and that I have nothing to be ashamed of.

Sometimes, though, I wish he had discussed his outbursts with me and I could have shared why I thought that was something I couldn’t overlook if I was to be a reference. That way he would have known how I would respond to an interviewer’s question before it was asked.