Here in Eastern Canada, the local bluegrassers are very particular about what kinds of instruments "qualify" as true bluegrass instruments or not. In particular, the only form of percussion the purists will allow is a solid "chop" on the mandolin.
I was told about a campfire jam session at the Stan Rogers Festival in Canso a few years ago. Local legend J. P. Cormier was there, and some newbie showed up with set of spoons. He did his clickety-clack thing through the first couple of tunes, before J.P. asked if he could see the spoons, saying he had never heard such a unique tone from a set of spoons. The chap felt honored that his kitchen spoons had impressed J.P. so much, and gladly passed them over. J.P. stood up and drove them a long throw into the nearby woods, and said to the guy: "Don't ever bring a set of spoons to a bluegrass festival again!"
Buddy was quite shocked, but the point was made and everyone had a good laugh.