I agree with FLU. I once worked for a company that did credit checks upfront and obviously never followed up after that because at least two employees I knew subsequently had BKs and the company never knew.
What I find fascinating is that, according to an article I read recently, more and more employers are searchimg myspace and Facebook to see if a potential employee is a whack job. There were a few interesting examples in that article about people who weren’t hired based on those searches (the person posed with a rifle and such).