Mmh, I don't know but there's no foul taste to me. I regard them as kings of execution. Yes, they don't "invent" business models but they take what works and execute on it. Nothing wrong with that - it's how most business made money for many many years.
They don't just copy business models - in most cases, they straight-out clone entire sites/products and resort to poaching to force the "competitor" (original product) out of market.
