I went to my haircut with hair longer than my nipples, wanting a trim. I came out with shoulder length hair. I asked for layers all round, and came out with a blunt cut. It went wrong when the stylist asked me 'Maximum short?' and I gave them my absolute maximum for the layers - not expecting that all of my hair would end up that length.
I was also in and out in only 20 minutes - fastest wash, cut and blow dry I've had. It felt rushed through. Would never go back.