Are you sure it's dirty marks and not just absorptions of conditioners? Can you show what it looks like/
Working on pics - barely any room on the hard drive for phone sync...need DH's help first! Maybe in the next day or two...
The marks do look like dirt and not just conditioner absorption - faint grey tinge to them/dirt like and not darkened same colour leather type streaks from product.
My DS dropped his bottle on the bag the other day and the milk beaded off/easy wipe no mark left over. I want to do a bunch more B&O and also wanting to do a good safe cleaning first since the bag has been in rotation for a couple of months... Is it safe to try a Lexol wipe?