Every once in a while, HR professionals and recruiters come across a near-perfect candidate. His skills and expertise perfectly match what you're looking for, and culturally, it's a perfect fit. There's only one caveat: he has a bad professional reference.
Should you believe it?
Bad references are something that everyone has to decide whether or not to reconcile with. Here are some things to consider when choosing whether or not to ignore the reference.
Did it happen a long time ago?
Everybody makes mistakes and does stupid things, especially when they're young. Poor decisions have a way of coming back and haunting people, after all. But if something bad happened years ago-- an error in judgement, or perhaps a minor conviction like a DUI-- and this person has had a spotless record since, it may be wiser to cut some slack.
If nothing else, ask the candidate about the incident. Raise your concerns and allow them an opportunity to explain themself, as well as what they learned from the situation. Someone who has messed up and knows how to recover may actually be more valuable to your organization.
Is the bad reference for a completely different job?
The kind of skill set, habits, or personality that may make someone terrible at one job may make them brilliant at another. An introvert might be terrible at sales but great at resolving internal process issues-- likewise, someone who is miserable at developing might be a whiz when it comes to technical writing. Listen carefully to the bad reference, and decide if the person's weaknesses in that position might be strengths in disguise.
Is the bad reference an outlier?
Perhaps you've called up an old boss that wasn't listed under the candidate's references and he has nothing nice to say. Every other reference though-- listed and unlisted-- is positive. So should you believe the bad reference? Probably not, experts say-- chances are, it's a personal problem with the boss, not a general issue that you'll experience at your job.
Sometimes, personalities clash, despite everyone's best intentions. Or, this could even be a good thing: bad bosses often feel threatened by stellar employees, and trash them for working too hard.
Of course, it's always important to exercise your own best judgement when making a hire, and that includes carefully evaluating what you hear in references. Hiring an employee is a risk no matter what-- even an employee with glowing references may be a poor hiring decision.
Take into account your own impression of the individual, and consider what you heard in the references within the context of your organization. Everyone makes mistakes and has bad experiences from time to time-- both employees and employers alike. The most important thing anyone can do is learn from those errors and move on.