For coins like this, my take is that grade doesn't matter - what matters is eye appeal. In this case there obverse has almost none and the reverse is only sightly better Things I've been told to look for: toning that is even across the entire surface (strike one), if not even the toning should be symmetrical. Ideally this means bullseye toning (strike 2) or left/right or top/bottom symmetry (strike 3).
Coins that are exceptionally rare can sometimes be collectable, though damaged or ugly ducklings like this one. But I would say that this one is a place holder and not much more. It may be that an acetone soak clears some of that crud up but I suspect that's unlikely.