The only time the "flipped back" has been allowed as a variation is when it was done within a specific release type. The lone exception that I know was granted was the 1987 Donruss baseball set where the only the factory set cards were printed with the back flipped the other way. This seemed to be an intentional design by the manufacturer (but knowing how sloppy many companies were back then, probably not), but it was an identifying "mark" of the difference between cards issued in packs and those from the factory set. Admin allowed those, but not ones that are "accidental" - as in the ones where you've opened 1,000s of cards, you have 20 of card #362, and 1 of the 20 has the back flipped. I pulled one like that out of 2012 Topps and it was not allowed. It was considered a printing "glitch" and is not listable.
As with other printing "glitches", the fact that it's not listable here shouldn't detract from any potential value of or desire to own the card. There are plenty of collectors out there who are looking for "odd" stuff, and cards like this are right up their alley. TCDB-listability and personal collectibility are separate things.
-- Dan --
Note: Please see my profile for more info regarding trading (section updated 3/4/2024). I have added a large portion of my inventory to the site, and currently have trading turned on (details are in my profile).
