The Archive.org scan of an Ohio Adjutant General report of War of 1812 for a unit of interest was a little difficult to read in spots. Ancestry.com had a scan of the same publication that was easier to read. It may have been made from a copy of the book that had seen less wear and was in better shape.
This is not to say that Archive.org is always bad and that Ancestry.com is always better--that's not the case. Sometimes it's the other way around.
It just pays to look in more than one place if the image you've located has portions that are difficult to read.