Do you live at the same address and/or share a last name with the person(s) who might add you as an AU? If not, the AU account(s) might not show up on your credit report and/or not have any impact on your FICO.

I've also heard that AUs are less likely to appear on a credit report if an SSN isn't attached to the AU account. Many CCs allow people to add an AU using only a name or name and DOB. (I was an AU once using the latter method, and the account only showed up on one out of the three main credit reports.)