The quality of the writing and printing are also good clues. We intuitively know how all these things fit together to make a package of information we can understand. Most people, particularly in the IT industry, do not have the skills, time or interest needed to understand and effectively structure information in ways that readers understand. Librarian skills are invaluable to those companies like mine, who work with already created information, and whose expertise is in re-crafting a clients information so that it works just as well or even better on a screen than it does in the static medium of paper. Now here's another area where librarians can use their existing skills in the world outside libraries.
Librarians are effective information finders.
We look at a suite of knowledge, in a book, on a shelf, in a catalogue, and know what combination of skills we need to put together in order to use that suite of information effectively. We know we use different searching and discovery skills for different types of information, and even the different mediums - for example we use different skills to search an online database than we use to search a card catalogue. Many people who are creating information today, are unaware that readers bring different search and discovery skills to a screen based interaction than they do to a paper based interaction. Authors and publishers are finding out that you can't just take a piece of knowledge structured and written for paper and plonk it on a screen and expect readers to approach it the same way as they would have on paper. A good example of this is some recent work we did for dept of defence in the lead up to y2k.