Sharp talked about banjos as "nigger machines" and ignored them

Where is this quote from, Jim? I haven't come across it in my research. Sharp did occasionally use the 'N-word' in his writings, but more commonly used 'negro' and, described the two African-American singers he met as 'coloured' (which was at one time considered the politer term to use). Bear in mind also that the white mountain people he was working with routinely used the offensive term in 1916. Although Sharp certainly shared some of the racial ideas about white (and specifically English) superiority Pseudonymous was describing, he made some complimentary remarks about the few black people he actually met.

Although he was far more interested in unaccompanied ballads than banjo music, he did say after hearing a banjo / fiddle duet:

"The thing was very skilfully played, plumb in tune, and its constant repetition had a very hypnotic effect on me and apparently on the players ... the tunes look little enough when committed to paper, but the way they were played produced a very curious and not un-beautiful effect."