That's kinda the point of authentics. You're supposed to wear the fuck out of them and make them the most comfy shoes imaginable.
But I have the same problem, I already sweaty feet and when I go sockless my insoles turn black and have a thin layer of much on them (yes, I know gross) but all you have to do is make a thin paste of baking soda and water and scrub the insoles and they look brand new.