I have seen quite a few prints recently where “paper white” is showing. By this I mean an area of pure white, either overexposed or badly edited to the detriment of the image, so that when printed nothing is rendered leaving white paper showing through.
Why is this a problem? Because the reflectance of the inked paper is different than areas where ink has been applied, like a scar on flesh.
This is easily spotted by watching the histogram and also very easily corrected. Very small areas can be dealt with by modifying the image in Photoshop so that the out put of full white is reduced from 255 to, say, 248. Alternatively create a new layer, fill it with white with a value of 248 and set the blend mode to darken, either way the print will now render correctly without ugly bare patches of “Paper White” showing through.
Neither of theses tips is the perfect answer. Ideally you should watch the histogram while processing and not let the highlights blow in the first place.