What are blank pages and why would you want to look at them?
The BHL book brings up an interesting point: as BHL is a consortium, the members are able to make their own calls (TO AN EXTENT... beyond this we get into a lot of nitty gritty) on how they digitize. Smithsonian Libraries, for example, makes a point to scan all pages front and back, while other partners (such as Harvard MCZ, apparently) don't. It raises an interesting point about who libraries think are looking at their digital objects: BHL's core goal is communicating biodiversity literature, not necessarily the physical objects, so scanning blanks was not a priority for them. On the other hand, the rare book librarians at Smithsonian Libraries have had a LOT of input on scanning, so our digitization crew scans blanks, pastedowns, flyleaves, the whole shebang!