I hope you didn't take me as saying they didn't work?

Not at all! You're one of my regular (and treasured!) readers so I know you're very familiar with my characters and how I interpret Tolkien's legendarium. :^)

It also reminded me of those old theological debates whether evil is in itself an entity or merely the absence of good and the result of error...

Oooooh, yes! Speaking for myself, I take a humanist's view of evil and that's reflected in my fic.