I think that there are some interesting ideas being explored in this thread and would like to recommend a recent Musical Traditions article:

'Bob Blake and the re-invented self' by Mike Yates, MT article 184, 8.8.06.

In this article Mr Yates discusses one of his informants, Bob Blake who, it turns out, didn't fit the mould of a 'genuine' traditional singer (whatever that is!!) quite as well as the collector originally thought he did. It's a brave and thought provoking piece and I recommend it highly.