I think your all out of wack if you perform a background check on a hacker other than for purposes listed below. Unix is evil. Daemons run wild. Zombies roam and children are killed. Sometimes, you just gotta take a chance.
Criminals come in all flavors.
You might never know you've hired a hacker until it's too late. You have to use judgement and ask the right questions during the interview. A candidates answers to certain key questions will alert you to certain mindsets and motivations. I don't use that term much except with oysters. I don't know.