Well, the kid I bought them from had bought three cases because he wanted a foil Birds (which, coincidentally, he said he didn't get), and that there were occasional blanks in the common, frequent blanks in the uncommon, and very occasional blanks in the rare slot in all of the boxes.
Er, I think I get what you mean--no, this was not "he opened a booster and found 15 blanks."
--J
Dan: I received your PM and reviewed the cards via the scans you provided. There is no need to send me one for personal review as I can easily confirm these as fakes/man-made just from the scans. A filler card will be devoid of all ink discoloration and be purely white on the card front. Zooming in on the front, you can easily see in the lower left corner, residual ink pixels left over. They are bluish in color, proving the black in the border area was faded or washed in these few missed pixels. The sleeved pic has the same pixelation in the lower left as well, although the sleeve scan came out a pinkish hue. What definitely gave these away as fakes/man made are the backs. Nearly all edges on the back have chemical wash marks on the back. Your sleeveless scan is upside down, but I will point out defects as if viewing the card normally upright. The marks are along the bottom of the card mid way, the top right, and god awful all down the right spine. The extra chemical damage on the right also shows the card was picked up from the left side, thereby exposing the right to more acetone as it would have been dipped in. The sleeved pictures show the same levels of chemical damage. Your digitals show me nothing more I need to see. Hopefully you did not give an arm and a leg for these as you have been taken by faked blank cards made from real M:TG cards.
I am often used here to validate cards or rate card conditions (most of these privately), and I hold much credibility in the community to do so, even via scans alone.