I don't know, but do they lower your credit score if you:
- forget to pay a credit card on time but they waive the fee as if nothing happened because you have a good long history with them? Fully paid right before asking for the fee waiver.
- open credit cards or bank accounts (all approved)?
1) As stated, depends on if your credit card reported you delinquent, which generally will only happen with zero contact from you for 30 days. If you are going to be late, or can't afford to pay, call them! They will work with you, even if it might cause a temporary freeze in using that particular card.
2) Yes, and no. Applying for any credit will give you a hard inquiry, which does lower you score, however, getting approved will give you another account and possibly increased available credit. That can raise your score.