And just becasue someone has a bad reference doesn't mean they are bad, it might mean they worked for someone vindictive.
I actually hired someone because he got a bad reference from a previous employer. I was checking his references after the initial interview, and saw where one of them was a local web design/programming company that I had dealt with before. This particular company had a reputation for being sneaky, dirty, and underhanded. The owner/lead programmer would lie, cheat, and steal for a dollar, and no one could work with or trust him. Everything he designed was junk, he would intentionally build something that would break so you would have to pay him to come back and work on it. He also had a bad habit of always pointing his finger at someone else and never taking the blame for his screw ups. One time, he actually accused his competition of hacking into his customer's server and uninstalling all the Windows Service Packs because this customer got a virus on his server. The truth was, this guy had forgotten to Service Pack the server when he built it. Anyway...when I called for a reference, he had nothing but negative comments to say about my prospective employee. He talked about how this guy couldn't be trusted and how he had been "stealing" business from him, etc...
Since I already knew the previous employer, his negative reference told me everything I needed to know. I hired the guy. He has wound up being one of the best programmers I've worked with. Later on, I found out why his previous employer had been so negative. He had asked my employee to do something illegal, and when my employee refused, he was fired.
Now, of course, if I hadn't known the previous employer and his history, this situation would have most likely been the exact opposite. But, I thought I would share it with you anyway to reenforce SQLSister's point.
Hope This Helps!
Ecobb
"Alright Brain, you don't like me, and I don't like you. But lets just do this, and I can get back to killing you with beer." - Homer Simpson