"Quacking" is anytime somebody blames something or somebody else for their behaviors, feelings, and addictions and deflects attention off themselves onto the the other person.
It's basically verbalized denial that frequently takes the form of an attack or attempts to move blame for ones behavior onto someone or something else
frequently preceded by:
Yeah, but
No, YOU
If only YOU/He/She would
It IS devoid of meaning because the person in question has usually said the same thing 100's of times before without actually changing anything.