I actually was told that you can wash the "pliage" bags in the washing machine...
I've never done that though - at least not yet... Someone in the German Purse Forum told me, that if you put them in the washing machine the leather (the handles and the flap) get a lighter colour.
Throw it in the washing machine after you use some shout spray gel on the stain. The bag will be fine..just air dry, inside out. It will take a few days for it to dry fully. I stick my longchamps and my prada nylons in the washer and they are just fine. If you are nervous, wash inside a pillowcase (knot it shut).
Just editing to add that if you are still nervous :) hand wash in sink with woolite.
I actually mixed a little bit of laundry detergent with water and took a sponge to wipe off the marks. It worked out very well. I haven't tried putting it in the washing machine yet because I'm afraid of the leather handles being damaged.