So often when I'm out in a public area and I'm with my guitar, people come up to me wanting to try my guitar. Now, this isn't a problem at all if it's a competent musician that I know can be careful with the guitar. But, for random non-guitarists that just want to strum all the open strings, they don't know how to be aware of the headstock hitting something or scratching the finish with their belt, or the dreaded dirty hands. I don't mind sharing, it's just most people don't know how to treat a guitar, nor do people understand its value, whether sentimental or market value. I've had people mistreat my equipment before. How can one decline someone's request to play the guitar and then proceed to let a musician you know use it without coming across as rude?