Too often we will bring on a new hire that looked like a dream on paper but was actually a nightmare in disguise. I have more stories than I can count about hiring what seemed to be a mature, hardworking, level headed individual but in reality they had boiled bunnies in pots all over town! Why did I not find this out through an employment reference check? Because it is against the law for a previous employer to offer any information on a reference check other than the dates the person was employed by them and their salary. Therefore, it is imperative to have an accurate BS meter when interviewing people. Dig in, ask for examples if something doesn't sit right with you.
For my company I now require an applicant to go through several rounds of interviews. I even have people not connected with the role we are filling talk with the applicant to get a feel for the person. Still, people have slipped through the cracks.
One lady we hired, we'll call her Agnes, to support a top executive took the term "mentor" to a different level. When Agnes started, we assigned her to learn the ropes from our top executive support person, we'll call her Carolyn. Over several months Agnes and Carolyn became friends. They didn't get together on weekends together but they went to lunch every day. One day Carolyn made other plans for lunch but didn't invite Agnes. This infuriated Agnes to the point that she said something to Carolyn about it. Carolyn knew at that moment she had an issue on her hands and started backing off of the friendship. Agnes began to stalk Carolyn, driving by her house at night and showing up places where she would be out to dinner dinner with her family. Then came the threats, Agnes began threatening Carolyn that she would tell her husband about her affair (a secret among friends) if she didn't stop "being mean" to her. Carolyn got so uncomfortable she came to our HR department. We provided security for Carolyn. After an in depth investigation, we fired Agnes. Agnes then told Carolyn's husband about her affair which triggered a divorce and the loss of many hours by Carolyn to handle her legal affairs.
If Agnes and Carolyn weren't enough to deal with, enter Sophie. Sophie was very good at her job but had an overactive imagination. She often told employees that her fiance died in Desert Storm. It doesn't take a rocket scientist to find out that a hand full of people died in that war with only two of them being from our state -- none of which were connected to her in any way. This isn't against the law by any means and she was still very good at her job. Sophie liked the attention of senior management. After hearing through the office grapevine what was happening with Agnes and Carolyn, she came to HR too saying she was being stalked as well -- not by Agnes, mind you, but by a "midget" (using her terms). The VP of HR could barely get through a sentence without laughing hysterically when he told me about his claim. The whole situation was preposterous but it was obviously real to Sophie. We provided her with security as well.
As time went by this whole situation took care of itself as we ended up firing Sophie too and Carolyn eventually left on her own. That said, my company was still out the expense of countless hours and security costs resulting from these situations.
David Thomas Roberts is absolutely correct in his book Unemployable when he says the very nanosecond you realize you made a bad hire-- END IT. Your long term costs can be enormous with on-boarding, training, salaries, and benefits. I would rather hire someone with no experience at all who had a can do attitude and wasn't afraid to solve problems over someone with a pedigree of elaborate experience but can't get along with people. First, last, and always, your people are your most valuable asset so invest wisely and pull your money if the market is going south.