Background Check

Hey everyone! So after months of looking I finally was offered a job contingent on a background check. I'm wondering how stringent these really are and what disqualifiers they are looking for? I did spruce up my resumé a bit (no overt lies) and I also have a marijuana possession charge from many years ago that I did not disclose (almost sure that's been expunged though). Can anyone in HR maybe shed a little more light? Thanks!

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