i suppose a more adept definition would be a "hidden soul", to claim their attributes as soul, like you said, which is overshadowed by the appearance of the person in the context.
You're right that a material ugliness can imply a spirital grotesqueness, however i would go further and say that they feed into each other, directly linked. But its not a certainty, like you said, so there can be attributes that are positive that you're not aware of.
I see it like this, the anima/soul is the potential energy, or the particular goal of all beings, and the world works off of it. It goes down to the very material of things.
I dont like that idea, but i think it has merit in the fact that things are born with a particularities, however if thats to be believed it has very little impact because I acknowledge the transmutable being of a person being far, far greater, overshadowing the "base soul" or however you would call that
elaborate on what you think souls are, im intrested in what you're thinking