I'm afraid I fall into the group that loans out instruments when asked. I like to hear my guitar well played and It isn't something that happens when I play it. My guitar would be difficult to replace but it isn't any great or wonderful instrument and could be replaced once the money surfaced.

There is a corollary to this question though. Once you loan your stringed instrument should the borrower feel free to retune it? Many people seem to think it's OK but not all of them have a better ear than my electronic tuner. Sometimes they make things much worse.