For goodness sake, whether something is "folk" or not is nothing to do with whether you like it or not, or whether it has merit or not.

If I "should" sing folk (to come back on topic), how do I know what it is I "should" sing if the word "folk" has no meaning?

I bet you, LH, I could find you a folk song you hated, and also a snigger snogwriter song you hated, and a Dylanist (not necessary Dylan) song you hated etc etc.

In some cases it isn't the song, but the delivery. To me, Young Tradition's performance of "Henry the Poacher" is wonderful and vibrant, but Ewan MacColl's leaden and plodding.