This problem have mostly the books scanned by Google and Microsoft. And yes they were scanned by humans, the fingers are very often seen on the scanned pages. Google was using an automatic image processing algorithm to remove the fingers but it's far from perfect
Sometimes they also skipped over many pages which are missing completely in the scan. Google's scanning personel never opened folded tables, it seems they were forbidden to do so. I think their motto was more on quantity than on quality and making the scanning process as cheap as possible.
But there are also other digital librarys like Gallica (BNF) which did a very good job (color scans, very good resolution, all tables scanned in full size). In my eyes the most advanced digitalisation project in Europe, maybe in the world. They have quantity and quality.
Some years ago I was happy even about Google's scans because it was better than nothing. Now I have a different opinion because (at least some german) librarys (like bavarian state library) let scan their books by Google (in a worse quality) and now they say "hey, we have digitized our old books, we did our work" and don't improove anything.
I had a look for high resolution color scans of some books in German librarys. The average price was 5 € per page which is incredible high. A small book with 120 pages would cost 600 € - this is mostly more than if the book is for sale somewhere (sadly it isn't). Scanning the pages isn't a big job for the librarys. The "Bookeye" scanners which they are using can scan an A2 page in 600 dpi in 3 seconds. If this thematic would be in any of our party's program they would get my vote
@BMG50: did you find out the name of the book you are looking after? Is it a german book or maybe austrian?