Yes indeed the homepage is one big image. It's a temporary site for now as we build a proper shopping cart site. The deeper pages are simple html based upon another e-commerce site we run.
And again, well observed, some of the shirts have been photoshopped not onto another head, but onto real photos of people in shirts. That will change soon as we have shirts to shoot now, we didn't when we launched the site.
i'd like to suggest that you continue to 'shop the shirts onto other people's heads. just don't disguise it. there may be a fun and intriguing marketing strategy there.
really. the shirt is clever, and i'm sure you'll many more.