Good question... I don't know.

I can kind of tell when I'm presented with something, or come up with an initial educated guess anyway. But debate & discussion often sheds new light, new information, and a new perspective that can change my initial assessment.

In terms of design in this context, I tend to think in terms of process vs. output. But that's a bias and shouldn't be an unconditional view. I think it helps to separate the 'creator' from the 'created' is all. It seems that everything that exists has been created by a process, and that everything that exists has a "design". It seems that it would be beneficial to separate the "design of a thing" from the "design of the processes behind creating a thing" in the discussion though. At least occassionaly, anyway. Not quite sure how to do that.