A literature search on problems with scanning and OCR (whether by Google or academic institutions) will quickly alert you to the fact that the original is still king/queen in research. Consider contacting an institution if you find problems with a scan. Below is a recent example on this topic; problems with scanning can occur at any institution and people who are passionate about making cultural heritage materials open to the public are usually happy to receive feedback and correct the problem.
http://commons.wikimedia.org/wiki/File:Google_scanfehler_wien.jpg
