Couldn't it be that 1% is fake site-wide, but that for some products, 85% of 600 reviews might be fake? If I were Amazon and would want to downplay the issue, I would certainly quote the site-wide figure when the fake-review-posters are only paid to hype a couple of products.
1% seems way way too conservative, every product I click has a lot of them. Even if you count all the products people don't buy much, it has to be at least 5 or 10% fake reviews minimum.
