Actually, my understanding of the story on Rubinstein is that he did not clean the keys of his piano, ever....normal use without cleaning resulted in a rather sticky, tractable surface to the keys to which he was accustomed. Once, just prior to a concert, a well-meaning stage hand noticed that the keys to Rubinstein's Steinway were horribly dirty, so he cleaned them. Rubinstein refused to play that night's concert because the feel of the key surfaces was so different. Everyone was in panic-mode. What to do? A call was made to the piano technician who immediately came to the hall and "fixed" the keyboard - after carefully removing it from the piano and masking the action, he sprayed a light coat of hairspray onto the keys. Rubinstein was happy and the concert was completed as planned.
I believe that this story is fairly accurate - my piano technician was an apprentice to the technician that "fixed" Rubinsteins' keyboard.