I think that you - or the seller mentioned, as the case may be, but I'll use "you" just to keep things simple - need to take the time to have
Coach items authenticated before listing, and this problem won't occur. The problems mentioned in those listings have been mentioned in several accepted analyses of invalid/fake serial numbers and those are available to sellers and buyers both here and at Ebay.
Sellers are always welcome to ask for authenticity opinions here freely as long as they follow forum rules and don't advertise or link to their listings or stores, and by doing so can have the benefit of several opinions to help them decide whether or not a Coach item is genuine. Ebay DOES require that all items be authentic, and if a seller doesn't take steps to be sure it is by getting other opinions, or doesn't take steps to find what details point to something being fake, they're not making a strong enough effort to be sure they're selling genuine Coach products, and they run the risk of having counterfeit items removed by Ebay.
A simple understanding of Coach factory codes would have shown the seller mentioned that several of those bags weren't even
close to having a valid month code. I can understand someone not knowing the plant
location codes but to not know that Coach month codes only go to "M", and on very rare occasions, "N", is hard to justify. That's basic Coach knowledge for anyone who makes a living or fills a need by selling or buying Coach products. And that's NOT the kind of mistake a plant would keep making over and over to where dozens if not hundreds of bags would be leaving plants with codes like "P" or "S" that have never appeared in genuine Coaches and most of which show up in bags with other problems as well.
There's no reason a seller can't take advantage of the research that members here have already done, and there's a ton of other useful information here as well. Or they can post their own photos at Ebay's Shoes & Purses forum and still follow that forum's labyrinthine rules by declaring in the post requesting authenticity opinions that they own the bag and the photos. Or they can use a professional authentication service. Self-authenticating your own listings is only for sellers who are experienced at spotting fakes and know where to find the information that helps them do it.
As for not recommending sellers - when a seller lists 3 or 4 counterfeits in the space of a month,
something's wrong. And potential buyers need to be aware that there's a risk factor buying from that seller that some of us find unacceptible, especially when it doesn't have to happen. Judging a seller "by their record" is all well and good, but when listing and selling fakes becomes part of that record, what then? Is everyone supposed to just ignore it?
Understand something clearly - NO ONE IS HERE TO HURT ANYONE'S REPUTATION. Everyone who authenticates here has gotten stuck with a fake at one time or another, and we don't want to see it happen to other people. The people in these forums who have taken the time to try and learn the subject of Coach fakes backwards and forwards do so for one simple reason - because we don't want to see anyone get ripped off, either deliberately or accidently. Even if a seller didn't realize a bag was fake, what about the buyer? Time AND money are lost since much of the time they won't be reimbursed for shipping charges if the fake has to be returned, and loss of trust in Ebay sellers in general and sometimes in the whole Ebay system. Nobody wins and everybody loses.