I play on an Ovation Balladeer. At my income level, that is a very expensive guitar. I'll let just about anyone play it as long as I'm there to watch. Ovation's have such a distinct sound and it's nice to hear it being played without actually having to play it.
I do agree with what everyone has said about tuning. I've spent thirteen years developing my ear; I don't like it when someone second-guesses my ability to tune my guitar, especially if they haven't been playing very long (less than a year).
I have noticed that no one is as careful about setting the instrument down as I am. People seem to have this bad habit of setting my guitar on its tuning keys, and that really bothers me. I also prefer to see it resting on the fretboard rather than the back of the neck.
--CS