The reason I ask is that I'm wondering whether the pictures showed the mark. Although it should have been disclosed, if you didn't notice it, that's on you.
While I do agree with this, I think it should be pointed out though (as with my recent experience) something can look one way in a photo and that not be the case. In my case with the Gucci bag (posted in the Gucci forum), in the photo it looked like there was a spot or blur on the seller's camera lens, yet when I received the bag in person it actually did have a significant defect on the fabric. Whether it was manufacturer defect or not has never been determined but regardless, when the bag has the tags still on it and is listed as new, you don't expect these kinds of things. Of course I opened a case and the seller claimed what you also stated in your post, that I had caused a stain and therefore was not happy and wanted my money back, but totally not the case, it was just a simple "hey this wasn't described correctly so I shouldn't have to pay what I did for it because had I known, I wouldn't have paid that price for it." Mistakes do happen but with how conniving people have become on eBay, no one knows who's telling the truth in a case like that. I had the same issue though, I tried to contact my seller and never got a response, which made me feel like she knew what was up and was trying to get away with it. In this case I wonder if the spot was covered on purpose or if the seller is just dense. Now, I just received an MK Hamilton, brand new with tags, and while it wasn't disclosed in the listing I did see in the photos a couple imperfections on the leather, but because I saw them I knew what I was buying and it didn't bother me and I wouldn't dare think of asking for a partial refund or anything.
Smells need to be taken with a grain of salt I think. My bag may not have a scent at all as far as I'm concerned, but someone else may be able to smell my perfume or whatever on it. Can't really do a whole lot about that if it wasn't described.
Now, my question is, was the bag stated as new or used? If it was stated as used, you HAVE to accept the fact that there will be imperfections (and I'm only referring to minor imperfections here) whether they are stated in the auction or not, it's just common sense, however I wouldn't accept a major flaw that wasn't described.