Ugh...I typically NEVER let anyone play one of my guitars. A few years back I made an exception for a young player from here in the area. He was maybe 15 at the time, but he's one of these KWS types who was wowing everyone with his abilities-mainly because of his age. He really wanted to borrow the guitar in the pic (Hans, you know it well), but I had to say "NOPE, there are only 8 of these in this finish, and 6 are in Japan." I will let you use my tried and trusted '95 CU22.
He was booked at our local fair-kind of a big deal for a kid his age. I met him and his parents at the local GC. I showed him the guitar, talked about the Dragon1 pups (at the time they were hitting $500/pair on ebay). We said our pleasantries and left. I didn't go watch/listen when he played the show.
So here's the kicker. We met a couple weeks later for me to get the guitar back. He said he really liked it. As a common courtesy I didn't open the case until I got home. He had broken the B string (I heard during an Allman Brothers tune), and the entire guitar felt like it was encased in grease! I've never felt a guitar that gnarly in my life! When I had let him borrow it, I had cleaned, polished, and re-strung it. Like Hans mentioned, I'm the same way: I give something back better than when I borrowed it. This was not the case here! It took me 2 cleaning/polishing sessions to get that "squeaky clean" feel back!
I am thankful I don't have the acidity or whatever it was that attacked 'Ol Blue! DAMN!