My least favorite is
Just be yourself!
Even in grade school I knew this was hogwash. I didn't act the same in class as during recess, or in church as when at the dinner table. Exactly which me was I supposed to be? When someone asks, "What am I supposed to do?" They are really asking, "How should I behave?" And if you've never been on a date before, or this is your first job interview, then it's not obvious.
A: "So, how did the interview go?"
B: "Not so well, he threw my resume away, in front of me, and ordered me to leave."
A: "What? Why?"
B: "Well, I did just as your said, I was being myself. I walked in, gave him the ol' finger guns, then started with my best fart joke."
A: "Why the hell would you do that at an interview?"
B: "Because that routine always slays in the dorms and I was trying to be myself."
Anybody on the autism spectrum just laughs sadly, shakes head quietly, when told 'just be your self'
"The customer is always right" conveniently missing the second part: "...in matters of taste and style".
Also misinterpreting "customer" as an individual rather than as the aggregate of customer demand.
Unsure if this counts as a quote but here goes.
If you can't handle me at my worst, you don't deserve me at my best
Absolute fucking nonsense.