I was curious what size these images are being displayed within Google Shopping, so I checked it out. They're displayed at a standard thumbnail size during search and a larger size in the detail view. At thumbnail size, the watermark is barely noticeable. At the larger size, it's clearly there but isn't gaudy or anything.

I understand the merchant's motivation for putting it there -- they don't want their images stolen and reused without attribution (although I wouldn't imagine there are a ton of people out there trying to steal images of CPAP masks).

I don't really understand Google's motivation for banning such watermarks. So long as they're not the type of full-image watermarks that cover the entire product and make it difficult to tell what you're looking at, I don't think they significantly degrade the user experience.

I guess what I'm saying is: Not all watermarks are created equal. The kind that make for a bad user experience should rightfully be banned ... but this is just a tiny credit line in the bottom right corner and isn't really covering up the image.