Dragging their feet to get out of the door... I'm perfectly happy to go over by 5 - 10 minutes if I haven't kept track of the time but some guys actually take the piss.
The most annoying client I've had: He's taken ten minutes to wash his hair, groom himself then with the most sort of aching deliberation spent ten minutes putting his clothes back on, all while asking me on a date??? Can that be two annoying things in one?
After taking his hand to lead him out the door (he wasn't getting the hint but I didn't want to be rude), I receive a bombardment of texts over the next few days asking me out for coffee, lunch, dinner. And he had the gall to claim that "I clearly had a good time" so I should see him for free. It's literally my job to pretend I'm enjoying myself, pal. Don't get ahead of yourself.