Those scuffs on shell cordovan will rub right out. A little Saphir Renovateur and a convex surface like a spoon (or deer bone) with gentle pressure in a circular pattern, and they will disappear.
That's the kind of stuff that you would accumulate after a few wears. I've seen shell cordovan 1sts look much worse than that.
If those were obtained at any kind of sale price, I'd happily keep them.