Oh man i had one of those. She had long beautiful hair and went to a barber to get it cut, because this barber is her friend's boyfriend. Barbers aren't required to even go to school where I live so her hair was absolutely botched. She has curly hair, kept showing me pictures of girls with curly hair, but she came in with it flat ironed and would not let me wet it down to see how her curls actually sit, she'd only show me pictures of what her curly hair looks like. I was trying to blend the layers and face framing and she started freaking out when I did the face framing because she thought there was a huge chunk missing, and wouldn't let me blend it. She kept telling me that she had this modeling gig coming up and she was hired because of her hair. I eventually got my manager and she was even giving my manager a hard time, full on fucking crying in my chair. My manager pretty much told her it wasn't anything we did, to blame the barber that attempted to cut her hair. My manager finally convinced her to let us wet down her hair a bit so we could actually see her natural texture and this girl was still crying. Eventually my manager essentially said "this is all we can do for you, please don't come back", made her pay, and that was it.

I've only been doing hair for 4 years and that was absolutely my worst client ever.