[Groxx]

If tied with a "make a paid account to access the obscured images", the non-obscured images may be useful enough on their own to be worth the initial buy-in. And the obscuring makes for a pretty strong block on use without at least some payment, as it's far harder to remove than most watermarks.

I do agree that a watermark is (strongly) preferable for choosing which individual images to buy - small details can make or break images, and this obscures a lot of the image. Just pointing out that there may be uses on the same kinds of sites.