I've had good luck checking references without credit or criminal checks. If the stories don't match, something smells. Credit is (IMHO) useless, since most small landlords wouldn't know how to report bad tenants to a credit agency anyway. Criminal can generally be found by searching through Google news archives if it's major enough (and then searching court records for disposition of the case). Also, sex-offender registries are free to access. If it's not major enough to make the papers and the sex-crime registry, I'm probably not going to worry since everyone is entitled to a few mistakes.