My thanks to Chris for this valuable lesson:
"..Here's something you might want to add to your fakes section. I've always
collected civil war hard images because I thought they were harder to fake
but now I'm not so sure. I purchased an ambrotype last year because I
thought the guy in the image might be military and I thought I might be able
to pull something out on the buttons. I scan the image and couldn't pull
anything out on the buttons so I resold it last November on ebay for $20. I
was surprised this week when I saw the same image I sold but he had grown
corporal stripes and cuff pipping and the buttons are now gilted. The seller
was the same guy I sold it to. I emailed him and he claims he doesn't know
how the image got altered and claims to have bought it at a gunshow. The
auction disappeared the next day. I've attached the
scan I used when I sold the image and a jpg from the auction this past week.
I hope you will add this to help educate others of the dangers of ebay."