I already inquired about this bag. It's authentic, but the color is off.

It could be just a lighting problem...If you are really interested in the bag, try asking for more pics (preferably outdoor ones). Somehow I have a feeling that it's just poor lighting and photo-taking skills (because I doubt someone would let their bag sit in a spot that allows it to be damaged by UV light). I also looked at my Vintage Flowers bag, and realized that it looks very different depending on the lighting (in some lighting the logos stand out a lot, while in others they tend to shy away a bit).
I hope this helps! Good luck with this auction (it may sell for a lot)!