Speaking of "fecetiousness" one of my favorite expressions that's often misused is a variation of "taking something with a grain of salt."
In contemporary parlance the phrase has no meaning. What do condiments and dubiousness have in common?
The original expression was "dose of salts" which referred to taking a laxative.
So when I suggest that others take my advice with a dose of salts you can be assured that I, not they, may be full of it.