Do "Ghost" images on backs of cards impact grades?
 

I have seen "ghost" images where ink bled onto the backs of cards, many on 33 Goudey's but i am sure it is prevalent on more than just that. My question is, how does such a thing impact the grade? Is it considered a print defect similar to poor registration, off centered cut or other print line?

it is a printing defect but one that can actually raise the value of a card, depending on the player, set and severity of the defect. A really sharp ghost has a ready market among a dedicated collecting base.

Thanks. Outside of collectability, do you know how PSA/SGC treats them? Is that a stain, defect or downgrade on grade in general?

Never used to, but I've had 2 cards which looked like psa 5s with printing errors on the reverse come back both as psa 3s.

YMMV