I work in high security IT and you can't have had a Felony in the last five years and a huge list of specific offenses that you can't have had for 15 years. Then there is something about large debt and who you owe it to as you could be compromised via financials. We didn't have a huge applicant pool to begin with so when so many bombed the background I was pretty sad.

Edit: I want to note that I don't get to see why someone failed nor any specifics. We go out of our way to avoid violating privacy as it is a big deal where I work.

On my team there are three guys 2 years out from retirement. Last time we posted one of their positions we had one applicant that passed the background checks. So when all three of them go I'm not sure we will be able to replace all of them. It's gonna be a bitch.