I should make time for posts like this more often but here's a little rundown on why people shouldn't use cheap scanners to archive material.
Take a look at this scan of an original old pin-up page that was sent to me this week, compressed as a jpg. At a glance it looks great with the watercolor paper really showing its tooth. (Technically the page has also not been laid down flat enough and we're getting an uneven light but let's overlook that.) Above shows the full art which was scanned large–about 11" tall at 300dpi.
Looking closer you can see that the mottling (modelling? now I'm not sure which.) is actually quite inconsistent, made up more of a kind of binary than a continuous tone. Her skin looks blemished. The wall just looks awful. Cheap scanners tend to blow out the highlights and sink the shadows. It's like getting the box of 8 crayons instead of 64, so the scanner relies more on contrast to form the image and you lose detail.
If you then compress that file as a jpg, it makes those tones crumple into jaggy pixelation. Everyone should know this by now but it's amazing how few people do: Jpg files are for the web. It makes your file size small so windows load more quickly. Most of the time there's no good reason for large files to be saved as jpgs. You want .tif (or .psd) for your precious artwork. If you save it as a .jpg you better have a reason. If you don't have a reason I hope you get stuck in an elevator with Jordan Crane, who will tear you apart without pity. (Go NOW to download his Reproguide at the bottom of this page .)
This last detail really showcases what makes cheap scanners the devil's work. The artwork is technically high resolution enough for print but if it were run at actual size you would see how awful the shading really looks. You would see how the highlight shading is a bunch of tiny gray boxes. The jpg compression is also making for all the little noise that's going on along the edges of lines.
As it is I'm probably going to use this file for print but run about a third of the size of the original. For the purposes of a non-archival project such as the Pin-Up series I simply don't have the luxury of controlling the work as much I'd like, besides the fact that most of the material will be scanned from old pulp digests.
It helps to explore compensatory tricks– I originally planned the pin-up series to be embellished with a second spot color not just because it looked cool and mirrored the coloring of the digest covers but specifically to draw the eye away from the generational loss of scanning continuous tone artwork off of crummy, 50 year old pulp.