If you don't expect someone to look at your computer whilst repairing it

...you deserve to get caught.

One would also hope that if a customer had porn on their hard drive, they had put it through their own personal taste filter, so to speak. Which might be either good, or bad, depends on your own perspective.

I don't really need to recount stories of pretending I didn't see various data on systems to spare the blushes of all concerned, do I?