Here's mine after a month and a half of use without a case from day one (arrived in immaculate condition). Daily use includes sometime going to construction site, daily walk with my dog (pulling it in/out often to snap photos), trip to the gym and constantly going in and out of my jean's front pocket. The only precaution I take is making sure my keys and coins go into different pockets.
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The only scuffing is near the headphone socket- I constantly hit it with the jack.
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While I don't think there's anything wrong with scuffed phone, my opinion is that with minimal effort (provided your phone arrived with no anodizing defect) the iPhone 5 finish can stay scuff-free (or with minor scuffing, chipping) for quite a while.