Actually the level 5 photo does not look good to me. It may be a photographic artifact but I'm seeing this big, irregular cloud of greenishness. Of course my visual cortex has been sensitized by hours of looking at my PW screen, which has similar clouds of pink and green (in my case mostly pinkish).
I think there's some sort of prism effect going on that is separating the white light as it passes through (or leaks into) the capacitative layer. Slight variation in thickness could account for it. Some units have more variation than others, ranging from better to worse.
I do think Amazon's suggestions about appropriate lighting level are spot on, however. In a dark room even 5 is way too bright, and I can even read at level 0, once my eyes adjust (but different PWs appear to have different lighting ranges).
I don't expect a 'paperwhite' screen in all situations, but I do expect neutral, off white color.