As should be known one may not use them in white Xperia S, as this then probably rubs and black streaks leaves.
Since both devices, both white, and black, have a special coating, it may also be that this is attacked by the lining of the bag. I think this is more likely, since at one of my other white Xperia devices (no S), this coating is not there, the bag but does not stain.
Exactly I can alerdings not say because I have a black S, thus can not assess whether the case now rubs off, or the coating acts.
Therefore, I have decided micht, despite that the bag fits well to use for S another.