I wouldn't think so. Again, simply making her an authorized user on his credit card doesn't mean her prior present or future bad credit goes on his reports other than that specifically used with that specific card she is authorized to use. Now, if Bob on the same account he authorizes a card for Alice on, destroys his credit with that card, in turn that negative credit will also appear as it relates to the use of that card account specifically on Alices reports as well.