Removing mark from shoe

Hi ladies- I mostly stay in the ebay forum but I'm venturing over here to ask your help! I bought a pair of Prada shoes a while ago at Bealls Factory Outlet in Orlando. They have a HUGE black mark through the middle of the inside of the shoe (you know, the ones that help prevent returns for full price) and it drives me crazy! I've worn these shoes a lot and the soles are quite scuffed so it's not like there's a chance of me taking them back LOL. Normally I don't mind the small black marks but this one takes up the whole length of the inside. Does anyone have any idea how I can remove it (or lighten it)? Has anyone had success in removing one before? Thanks so much for your help!
 
Since its the inside of the shoe and you have no plans on returning it, have you considered using a Mr. Clean dry eraser pad? (at least I think thats what they are called... maybe magic eraser) Anyways they are really great and getting out difficult stains such as scuff marks on walls... this might work, but you have to be careful as if you use it too hard it can be too abrasive. Good luck!
 
Kind of off topic (but not really)- I know some people sell their shoes on ebay that they bought from discount stores so that's why the inside is marked, but I've noticed on some ebay auctions for USED shoes the women say in their description "I will mark the inside of the shoe so you can't try to return them to a store." First of all, the bottom of the shoe is scuffed so it can't even pass for new, and second of all, what does the seller care? Those always make me chuckle.
 
Alcohol does really well for getting Sharpie off hard surfaces. It might work for your shoe, but I'd try a small spot first just to make sure it doesn't mess up your shoe.