Had seen that listing on Ebay earlier today before reading this thread, and assumed that the seller was falsely (or mistakenly) hyping a marked card. It looks like a purple stamp of an "8" to me. Am fascinated to discover that there are other cards with the same printing in the exact same position - lends credence to SGC for assigning a numerical grade to the card rather than going with an Auth designation for it being marked on the front.
But if it's a printing defect, like a wet transfer as mentioned earlier, then two questions:
- how come there's no other evidence of wet transfer on the card (eg ghost image, another color, etc. -- ie why is the red B the only element transferred)
- and the misprint doesn't look like a "B".