Yes, the flipside being of course that "Buyers are liars", that is they will play coy with the state of their carpet - Not the best example but a guy an Asian guy (not that that should have any bearing) agreed over the phone that his carpets just needed freshening up, and not a deep clean as he was moving out and ending his tenancy.
When I arrived there, rotary in hand (15th floor in a block of apartments) - there's crap all over the floor, and the carpet is in a right state. I did the best I could, but there certainly wasn't a great result. He paid, and moved to Saudi Arabia the next day, but I could tell he was expecting better.
I do like my customers to have a realistic expectation of results before I begin, but at the same time I'm not going to walk from a job that I've just spent 45 minutes travelling to because the customer told me some porky pies.