No open furum like this should ever include attacks or even strong criticism of source singers dead or alive

That's ludicrous fetishism.

And horribly destructive to the project of making the music moire widely known. If you tell everybody curious about folk "sorry, any doubts you may have about the quality of any of this are out of line" nobody will give it the time of day.

Irish trad buffs are happy to admit that Michael Coleman's pianist was a bozo. Klezmer buffs would tell you the same about Belf's. Why should it be different for singers in the British Isles?