I've thought some more about these bookscans. I think that even though the copyright on the original material has expired, the scan itself is the property of whoever produced it. Copyright notices and watermarks are nice, but scattered digital irregularities might also be useful in proving that someone has lifted another's effort.
ML/NJ
That doesn't make sense in the case of a blogger whose scans have no
copyright restrictions. Since he's not asking for any attribution, even when selling the scans, there's no reason to use irregularities or watermarks.