I guess I've been lucky. Can't say as I recall ever having a terrible guest. When I've had guests that know nothing about sailing I tell them how to stay out of my way when I have to do things.
Perhaps a recent frustration comes to mind from last year. I was out sailing with several folk that knew nothing about sailing but wanted to learn. We'd been going through how to put sails up and down, where all the halyards are, all that. We were now on day two of sailing...
We were out in a nice stiff breeze and there was a jet skier that had gotten a line tangled in their prop. They were calling for help as they sat on the nose of their jet ski. I couldn't figure out what exactly was happening at first, with the wind it was hard to hear them but they were waving their arms and looked in need. So I sailed over past them and we realized what was going on. So I said we had to drop the sails, and come u t them under motor. There was simply too much wind and waves to be as controlled as needed to pick someone off a jet ski in those conditions without smashing the person, the jet ski, or my boat.... As it was day two of sailing, I figured dropping sails would be easy. However, those guys took so long to figure out how to drop two sails... I should have just told them I'd do it myself. That really tried my patience. It all worked out in the end anyway, we got the person off the jet-ski - they weren't hurt, only scared.
In all fairness, once everything was under power and I was driving the boat, while it took a couple passes, those two guys did an amazingly good job of picking that person off the jet-ski! Let me tell you, with waves bouncing you all over, wind pushing everything around, the timing and positioning to accomplish this is no simple task. The whole time I kept thinking about man overboard and just how frigging difficult that could be!
dj