It's not uncommon to see scans like this, it is very rare for scans to display the whites and blacks as they should be. But it is an easy 5 seconds to "level" the image to correct it. Eg. http://i.imgur.com/58MtEIv.png
Uploads like this one with grays instead of blacks and whites is just the result of a lazy or nonexistent editor before uploading.
...He must live in the States...I'm sure that owning hentai is COMPLETELY legal over in Japan...because that's where it comes from. (I'm referring to page 3...where it appears the cops are confiscating everything...)