I first became aware of the practice of flipping lens on simple single lensed cameras when I saw samples of a flipped lens Brownie Hawkeye at Flickr.com. The images showed exaggerated blurring and vignetting on the edges. These looked similar to Holga and Diana camera images and I was intrigued.
I recently saw samples of a flipped lens Ansco Pix Panorama and was inspired to give it a try. When I went looking for my Pix Panorama, I found I had 2. I knew that this was a perfect way of comparing a stock camera to one with a flipped lens.
These images are clickable for higher res images.
Would you like to try this yourself? I made a how-to video showing how to flip the lens on the Ansco Pix Panorama and posted it on my youtube channel.