Not sure if anyone here has been following the Amazing Spider-Man #700 or Superior Spider-Man #1 spoiler debacle but both appeared online. The last two or three pages of 700 were posted a few days ago, the leak apparently originated from a comic store in New York.
It's genuinely not possible for the leaks to have come from a comic shop; no comic shop will receive the book until tomorrow. (It doesn't go on sale until the 26th, however.)
I think the leak either came from Marvel directly or from someone connected to Marvel, probably for guerrilla/viral marketing reasons.
Also, I'm willing to entertain the possibility that this is giant fake-out and that what's leaked has no relation to what we'll see next week. I don't think this is likely
, but I won't dismiss it as a possibility until I actually have the book in hand.