@ilias, I've merged all your posts, it's better to see it all like that.
So far, I've only saw that dirt in the upper part of stickers, so the packet color fading into the stickers inside doesn't seem likely to me (it would be all over the sticker, right?)
Could be from the cutting process, the blade migh have some dirt after cutting so many sheets... Could be when stickers are being sort into packets, those "rollers" or whatever you call them, when "pushing" the stickers, can also have some dirt in one... I'm more inclined to this last option, cutting would only leave dirt right in the edge... But can be something else I'm not remembering.
About the other issues you got... Actually, I got them all at least once too... Those two small parallel lines were very common in some CL stickers I got from 2008/09, I think... The index finger issue I can't remember where I got it... There was also a very common issue in CL stickers, with some kind of nerve in some stickers... I still have some in Champions of Europe 1955-2005 and CL 2008/09 stickers (I'm too lazy now to take pictures of them

).
Complain with Panini America, they need to know their production has some flaws... Stickers itself are not cheap, you're paying 10x more of what they worth to produce, so at least, you have to get flawless items.