So a person who in their private life is a lier, a cheater, a stealer and only God knows what else in their dealings with people they know it is to be assumed that they will be ever faithful to the public (the people they don't know).
If they are like that, it will be discernable in their public life. No need to get into their personal relationships, and drag their family members -- who certainly should have some expectation of privacy -- through the media grist mill.