Oh, and RoyB, everyone knows that everyone likes to think they're special, and people with big egos (like most rock stars) like to think they're extra special, and even if they can't tell a difference there's a satisfaction in thinking you have the best.
Have some fun next time you have someones guitar in your hand, tell them something like "I had a few left over from Jimmy Page, so I changed out your guitar's electronics to a carber/nickelblatt pot with platinum pins and 24k gold grapple wing jammer grommets and a flux capacitor and you should notice a lot more sweetness, specially with the 3 and 4th string...." And they'll say "Wow what a difference..."
Heck, there are actually people who think a Murphy Aged Les Paul sounds better then the identical guitar without the phony knocks and bumps.