Fluff is any answer that describes a general tendency rather than a specific event. It is not useless — it is a handle you can grab.
The move is always the same: hear the generality, ask for the last instance.
You: Do you ever run into that?
Them: Oh, all the time.
You: When did it last happen?
Them: Two weekends ago.
You: Can you talk me through it?
The first answer was worthless. Four sentences later you are inside a real story with real details you could not have invented.
Practise the pivot until it is automatic. It is the single highest-leverage sentence in customer discovery.