I bought an SM57 kinda assuming it was fake, though now I'm not so sure - it was disgustingly cheap, but it came with everything the real ones do; clip, the snazzy bag, manual, a little velcro cable-tie thing, and a warrenty card with the right information on it that Shure have happily accepted as genuine.
However the build quality isn't quite there - the insides aren't very neat and almost look hand-soldered (I'm assuming Shure do it with machines). The casing is spot on though.
Sound-wise, I haven't really had a chance to record it properly; I've used it live and it works fine, sounds okay but through a PA it's hard to tell. The only thing I've recorded with it were some vocals, and I don't have enough experience with the real thing to say whether it sounds right or not - it needed a boost in the mids to make it sound anything close to usable, but it's certainly clearer and sharper than the other cheap-ass mics I have lying around.
Steve