Dave,
All collectors have to fix perameters, especially the part time ones with limited resources (not Sharp, I agree).
But quite often it does come down to the decision between recording say, a version of 'Lord Gregory' and 'Knock 'Em in The Old Kent Road' - be honest, what would you choose?
An ethnomusicologist, social or cultural historian, whatever, would not and cannot discriminate, but I think it fair enough for 'folk song' collectors to confine their collecting to their definition of 'folk songs' (ah - there's the rub!).
An interesting excercise for us has been to ask the singers what 'their' attitude to the different types of song in their repertoire - that's when things really got interesting.
Jim Carroll
PS Sorry again Joe - will try to remember. I live for the day when I can post as a member - is it something I said?