I've heard you can try denatured alcohol = but I would be afraid to use it on a Louis. Of course, at least with that bag - the ink is on the very bottom so it wouldn't be as noticeable. However, if you wear it kind of slung over your shoulder (if you know what I mean) it would be visible.
It's really hard to say - other than that - the patina is kind of pretty - I'm just afraid it might look worse IRL since it's so old. It might be great - especially if you get it at the rock bottom price - but it's just so hard to say. I usually, if I'm going for preloved, try to get one only a year or two old, if possible. Wait and get some other opinions too. Does Let-trade ever get Noe's in? It might be worthwhile sending an e-mail off to a few reputable re-sellers to see if they can find you a nice one too. Good luck!