Dylan, whose voice was once described in Rolling Stone magazine (I think) as sounding like a cow with its head caught between fence posts -— is proof that a Great Rock & Roll singing voice is not necessarily a *great* voice :)
That’s for damn sure. Up till about 10 years ago, his voice was used much like an instrument. Not pretty sounding, but full of wisdom, wariness and weariness. Now it is more of a croak, but sometimes he nails it. When I listen to Lonesome Day Blues, for example, I still hear it.