I've just encountered one.
New customer, house needs cleaning by the weekend, arranged to clean it this morning. Arrived and no sign of customer, Cleaned windows, left invoice and then received 3 missed calls and finally a text :
Apparently the windows are still dirty (despite the use of Virosol and two soaks before rinsing) and I'd quoted a maximum of 2 hours but cleaned it in just over 1...as customer was in but obviously hiding! I have offered to rectify any issues but as I'm old and tired something tells me it's better just to write it off.
Followed that up with another new customer who was delighted and has booked in for six weeks time.