Surely you're not suggesting that this was (or should have been) some kind of scientific study? For all we know, they might have shot another 20 women who looked much better in the self-description than the stranger description.

It's just an interesting visual way to tell a story about body awareness. And of course, the whole point is to reinforce the Dove marketing approach, which is still a lot more healthy and wholesome than the typical cosmetic pitch (i.e. you're not beautiful unless you look like a skinny white photoshopped supermodel)