From George’s Employment Blawg, Background Checks and the Job Search , some good advice:
Be honest, knowing that the truth is likely to come out. Many facts you would prefer a potential employer not know may not preclude your employment if properly and honestly presented. But if the same facts are discovered by the background investigator, and expose lies on your application and/or resume, you will be viewed as a liar, which is much more likely to preclude hiring.
So, one background-checking expert advises, “The absolute best thing you can do . . . is come clean in the interview process.”
As to the Internet “digital dirt,” take a good hard look at your online presence and clean up your act, if necessary. Better yet, don’t post anything anywhere online that makes you seem unprofessional or otherwise raises red flags to a reasonable employer."