The FCC rules don't specify what constitutes profanity (there is no list of words) or obscenity (there is no description of what is or is not obscene). Similarly, there is no listing or description of what is operation in community interests and needs, but the Commission can certainly investigate and open hearings if they believe that a licensee has done something that is not within such boundaries.
For example, there was a morning show on a small station in South Carolina where the morning show made "dirty" comments. Upon investigation, the licensee was sanctions for content. This is just one case of where the FCC has investigated and found a station and its programming to violate the broad responsibilities of licensees.
In a non-content situation, the FCC has lots of specific technical rules. But if a station is inspected and has what we might call "messy engineering" they can be cited for violating "good engineering practices".
In other words, there are many areas in which the FCC can investigate and sanction licensees for what might be called "bad behaviour".