Clearscan, while downright wonderful, does seem to be quirky.
On some reprints, it gets most of the main text. On others, it actually gets text off photos and schematics and approaches full search coverage.
It is even swift enough to find both regular and hyphenated words!
Sadly, clearscan is only available on Acrobat 9 professional.
It could get even better. It sure would be nice to be able to edit their fonts. And there is no easy way to fix search artifacts.
Carefully done hires scans appear to be a must for the best results. I'm not completely happy with our present uploads. But getting them in place takes priority over getting them perfect.