Imagine you're in the doctor's office and pick up Family Circle magazine to read. Someone has taken a Sharpie and written, "For the truth about this publication, go to familycirclefacts.com".
I would think, "Oh, a nutter with a blog about how he didn't like the letters to the editor."
I would probably not go to the website and I certainly wouldn't stop reading it because of the graffiti. In fact, I may even feel more on the side off the victim of the graffiti!
I've stuck notes inside wts publications in the public library, because it's the library's property and I could get arrested for stealing or defacing it. But magazines that are left for anyone to take for free? Those are fair game.