Who decides which is worse??

[JollyElm]

When a card is submitted for grading to PSA and it has multiple problems, conventional wisdom says the grader chooses which is the worse of the bunch and attaches that particular qualifier to the card, since they only use one on the slab. (I'm reasonably sure that statement is not 100% accurate, but rather I use it as a general assessment of the issue.)

With that being said, I ran across this card on ebay (not my card, nor do I know the seller, etc.) and saw the 'ST' qualifier. I thought to myself, "Seriously? The picture is falling off the side of the card! Shouldn't it be OC??"

s-l1600.jpg

In quickly looking at the auction pics, the 'stain' is not readily apparent, so it is most likely of the general see through gum/wax variety on either the front or the back. If that is indeed the case, wouldn't most collectors believe this card's O/C or MC anomaly is much more egregious than whatever stain is on it?? Granted, the slab isn't in hand (I know, I know, buy the card not the grade. Ugh!), so it's possible, but not very likely, that the stain is more serious than it seems.

My question is this: Who decides what specific qualifier a card gets when multiple issues are present? Is it up to the grader(s) alone, or is there an official hierarchy of qualifiers that determines which is 'worst,' sort of like how a flush beats a straight in poker?