Not so many in Sentimental Education exactly moral—but plenty of them pretend to be. These people are less concerned about doing the right thing, and more concerned with, well, themselves. Even the most morally strict figure, Madame Moreau, has selfish motivations. Bourgeois conventions (i.e., what the middle class thinks is proper behavior) dictates this behavior. And you know what? We're pretty sure Flaubert wasn't a fan.
Frederick's morality is questionable. We usually expect a lot from our protagonists, but Frederick doesn't really deliver when it comes to making the right choices.
Frederick's mother might be a pain in the neck, but she's just helping him do the right thing.