IMO it's a shame the uploader didn't do a bit of histogram tweaking first, eg:
Some folks may disagree, but I'd say it's a question of context; maybe you want to preserve the yellowed paper and faded ink on an old ad, but not on colourful art IMO.
Obviously, to avoid moire patterns, the work has to be scanned at a high enough DPI to resolve the printing pattern... the question then, is should it be blurred out, or is it an inherent component of the art form? I'm inclined to ignore Warhol's contribution to the subject and just make the colours solid like the artist's originals.
Scanning double-page spreads like this is a bitch; even if the book or comic is disintegrated and you can lay it all flat and capture the whole page so you can stitch it together properly, as can be seen in this example the printing is almost always inconsistent : (