Sorry, Guest, if I misunderstood you. Certainly I can make personal judgements about, say, Cecil Sharp's collection, in that there are songs there that I'd want to sing and others that don't interest me at all, although that's a personal judgement and I'd hesitate to call them "mediocre".

Your argument touches on a broader issue. Singers like me who appropriate traditional songs (and the very fact that they're old and don't sound like recently-written songs is a part of their appeal) will always tend to make value judgements about the quality of a given tune or lyric. Enthusiasts for traditional singing - like those involved with producing Musical Traditions - tend to be more interested in the singers than the songs. The modern view (cf. Sharp's) is that a given singer's entire repertoire is worthy of consideration, whether Child Ballad, comic ditty or Victorian tear-jerker. It was no accident that 'Voice of the People' included plenty of detail about the singers but very little discussion of the songs they performed. Taken to extremes, that approach can have more to do with sociology than music, and (my profession being what it is) I take exception to the discernable feeling in some quarters that the old songs should be left to die with the old singers, and that poncey, over-educated revivalists should give up and go home. That said, there's a great deal of extremely good stuff in MT, and (as one turned on to traditional singing the day Roy Harris lent me his Sam Larner LPs) I'm glad that those enthusiasts are willing to share their specialist knowledge with the rest of us.