Thats kind of a shame actually. I thought unobtrusive watermarks were a pretty great way to secure Ebooks.
Paizo puts a watermark on all there books, and its never been an issue for me. Ive still seen books that have been bought under a fake name and email floating around, probably bought with a giftcard. They are usually pretty nice about keeping their marks off of anything you are supposed to give out, or have other people look at.