Just looked at my 5s and iPad Air again, and yes, to the naked eye they are perfect. I looked at the chamfer by glinting light off the edges and didn't see anything. I also used my fingers along the chamfer, which would most likely detect any roughness my eyes missed, and felt nothing.
I also looked at the Al backs, and they appear fine (though they've collected some oils from handling). The polished logos still look fine, but I suspect if I used a loupe, I might see some very fine scratches.
If I used a loupe over the entire surface, I might see some minor imperfections, but I'm talking about 10x to 25x mag. It really isn't worth the effort to do that. First, I can't see that small of a feature at normal viewing distances and secondly, normal use could have already created that small of a defect by now (though I do take great care when handling them).
I would only consider exchanging the device if the defect was visible to the naked eye at normal usage distance. But, if it takes a loupe to see it, an exchange might not be worth the effort. Over the life of the device, it'll pick up microscopic scratches anyway.