Interesting question. I've never loaned out a guitar to someone. I'd like to think I would, but now, actually thinking about it...nope.
I've given guitars to people; a few to my son, one to a good friend, but that's different. If I did lend one to someone, I know I would automatically clean it, restring it, and set it up after it came back, because...well, I would just have to.
The odd thing is I LOVE it when a player comes over, to have them/let them play anything I own. I'm proud of them because they're all great instruments and I enjoy it when others enjoy them. But I don't feel the same way in reverse. I don't like playing other people's guitars. It makes me uncomfortable; probably because of my own OCD nature. I'll immediately see and feel things that are wrong with them: Intonation that's off, action that could be better, or just things about them that I don't care for but can't tell them because I don't want to seem as much of a d!ck as I actually am..."Oh this is great!" "really nice!".
A friend of mine just spent a fortune on a brand new signature LP model. A guitar I don't particularly care for in a disgustingly ugly finish.
He was so proud.
He insisted I play it, which I really didn't want to but did. So I played a few lines and a couple chords and handed it back to him "Oh this is great! Really nice!"