A person who is described as squeaky-clean is completely correct, esp. in public behavior, and has never done anything immoral. In the spirit of self-regulation, banks would have a real incentive to keep their affairs squeaky-clean. Example from the Hansard archive.

A person who is described as squeaky-clean is completely correct, esp. in public behavior, and has never done anything immoral. Prevalence of these health issues has soared in the squeaky-clean developed world.

Definition of squeaky clean adjective from the Oxford Advanced Learner's Dictionary completely clean, and therefore attractive morally correct in every way; that cannot be criticized an all-American boy with a squeaky clean image. The new leader was seen as being dynamic and squeaky clean.

Squeaky-clean means completely clean—as clean as possible. The term comes from the squeaky sound that often happens when you run your finger over a smooth, clean surface, like a countertop of a windowpane, or when you rub a strand of wet hair after it’s been washed.