I remember seeing Ralph in the late 70's and Curly Ray Cline did the sales pitch, "You can own this very banjo Ralph is playing here tonight." A great way to sell banjos but I haven't seen anyone else do it. I didn't buy the banjo but I did buy a Curly Ray key chain with his picture on it.
Haskell McCormack was making sales pitches for "old" Gibson banjos on stage with Lester Flatt back in the early 1970s. I was told Haskell never traveled without an old Gibson or two in the bus for sale.
I've heard it suggested that Earl did this too. Can't testify to it though.