Lets Talk About Shoes

After viewing http://www.nytimes.com/2007/10/11/fashion/shows/11SHOES.html I can't see the pornography that has been suggested is depicted in the shoes. I view the shoes more as a piece of art - it's a piece of sculpture. The shoes illustrate the principles of design I learned in my first art class over a decade ago: balance, proportion, rhythm, emphasis and unity. I do understand the depiction of pornography used in designer ads where the models are reclining back, nude, and only wearing shoes. That I understand, but the shoes themselves they're just shoes. I guess my question may be how do you distinguish between art and pornography?