Now there's a creative idea here, but I have to ask 'why?'. I really do have an open mind to creative shots but this probably falls into the 'I'm gonna shoot some feet in a weird way no matter how odd or ugly it looks' category!
For me, what I see is dirty footprints on glass and not much else, although I do appreciate an excellent DOF to get both feet and sky in focus. Composition presents the subject plainly with no other context to assist your title, such as an airplane or something.