When Hiring, Give Negative References More Weight Hiring isn't an exact science. However, calling former employers can be helpful, if you are willing to listen.

We recently were tasked with hiring a bookkeeper for a small business. One of our candidates -- we'll call her "Nancy" -- was very qualified. Nancy had worked for several small businesses and had experience with the trades, credentials that were particularly important to our client.

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Nancy also interviewed well and was extremely enthusiastic. If anything, she might be a bit too animated, something we don't normally see in bookkeepers. But the owner liked her and wanted to make an offer, if Nancy's references were good.

And that was the problem: Nancy supplied references from two former employers, plus a personal/character reference. However, another one of her former employers, whom we knew, while listed on her resume was not offered as a reference. During the interview, Nancy was complimentary about this employer and her experience there. Because we had a signed waiver from Nancy allowing us to to check her references, we proceeded to do so.

The first reference, the wife of the owner of the company, who had worked alongside Nancy, gave a glowing report, saying Nancy had been an asset and she was sorry Nancy had left. But the former employer whom we knew, who hadn't been listed as a reference, gave a completely different report. This former employer said Nancy had been terminated and would not be hired back. While this contact declined to go into explicit detail, we were warned us about the level of "drama" Nancy had brought to that office. And other improprietries were hinted at.

We called our client, telling him he should consider another candidate. At the very least, he should think carefully before hiring Nancy. Our client had another idea: Call Nancy's most recent employer -- the other employer she'd listed as a reference.

When we followed that request, we found that the reference listed was not the owner but rather a direct supervisor, and the son of the owner. He said they would miss Nancy very much -- that she had been the best bookkeeper the company had had. But the company was changing the bookkeeping position to part-time, corroborating Nancy's reason for leaving. We questioned him about Nancy's behavior and personality. He told us there were no issues.

We went back to our client. Despite our continued warnings, our client made Nancy an offer. She accepted.

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Nancy's employment lasted less than 30 days. During that time, she missed at least one day each week, giving various excuses; and through innumerable discussions with teammates, she left those fellow employees feeling less satisfied with their positions and the employer. In short, in little time at all, she caused the big drama we had been warned about.

The most curious outcome was that we found that our second-place candidate had taken Nancy's previous job with her previous employer -- a full-time bookkeeping position.

What can we learn from the tale of Nancy the bookkeeper? First, when checking references, go beyond those the applicant provides. You can count on candidate-provided references to be glowing. If you ever get a candidate-provided reference that isn't, you should run as fast as possible from this hire.

Next, when checking references, verify that the number you are calling belongs to a real company and that it's the one you believe you are calling. Verify that the person you are calling actually works for that company.

While this wasn't an issue with Nancy, we have had candidates provide names and numbers for people who said they were previous employers -- and they were not. You might be surprised to learn that there are actually businesses whose sole purpose is to provide candidates with fake references.

Look up names on LinkedIn. Look up numbers and names on Google rather than calling the numbers the candidate provides. It doesn't take a lot of time to ensure more security.

Finally, most former employers won't give information about a candidate beyond dates of employment and title. If you get someone who is willing to talk to you openly about a former employee, listen carefully. If you hear negative information, give it considerable weight.

Related: 30 Secrets to Hiring the Right People

Hiring isn't an exact science. You will get it wrong from time to time. However, calling former employers can be helpful, if you are willing to listen.