Transparency and Masks in Coverflow and Quick Look!
Coverflow and Quick Look are not the best for displaying complicated pictures. I edit a lot with Photoshop and photos with transparency are not displayed right in Coverflow. Quick Look works fine with transparency however. Where Quick Look doesn't work is with masks. Right now, the best to get a preview of complicated photos with multiple layers and masks is to open it in Photoshop. If you know about a Quick Look plugin that would read Photoshop files, please post about it in the comments.