What is that weird way that fashion models walk?

I have always wondered what was wrong with the coordination or the leg bones of many of the fashion models that have that peculiar strut when they walk? It does nothing for the clothing that they are trying to advertise, and distracts from what they are trying to accomplish. Even on the well known hsn and qvc televised programs,whenever there is a fashion hour, they wobble around also. Whats with all of that ? Has anyone found the reason for it? Just kind of curious. Thanks in advance for your comments.