I was in NMLC yesterday looking at a white (cream) bag, we were discussing keeping it clean, and the SA said she takes her off-white bag to her dry cleaner and gets it 'reconditioned' of some sort, but the bag looks like new. Guess you would have to find one who does that sort of cleaning.
We've had quite a few discussions about the dreaded ink marks on bags. Beanie a supreme collector has a fabulous source to take care of this. It may cost you a little more but apparently the results makes it worth the while. Read below.