Well, Dead Horse, let me introduce myself. I'm Bill and I'm a borrowholic. Just kidding, sort of. I think I am a "serious musician", and I occasionally ask to borrow someone's guitar at a session. Usually cause I brought a mandolin and a fiddle but not a guitar (see that thread-without-end "Bad Manners at Sessions", another frequent pet peeve is people who bring too much clutter), and have an urge or a request to sing a song.   The hell with "the done thing", we're there to play--and share. What you share is up to you. I'm a guitar and mandolin enthusiast and enjoy trying different ones, and sharing my own with like-minded people.

What in my books is not 'the done thing' includes:

• not asking the owner first
  
• not taking a polite "no" for an answer--no explanation is required
  
• asking to try an instrument you don't know how to play
  
• obviously, abusing a borrowed instrument in any way, including unauthorized retunings, or putting it in harm's way
  

But I can't think why I'd want to be hanging around at a session with a bunch of people I wouldn't trust to play a tune on my instrument. Doesn't say much for the quality of musicianship present.

Tyke, most professional mechanics have a sign on their toolboxes "I make my living with these tools. Please don't ask to borrow them." Maybe you should try something like that....

W-O