Ithaca May flowers
I'm slowly realizing that librarians are biased. I don't know why I didn't think about this sooner. I suppose going through library school and realizing what's involved with being a reference librarian made me think that reference librarians knew as much as there was to know about information resources. Even though it was pounded into me that the real skill is knowing how to FIND information, I imagined that reference librarians memorized lists of particularly wonderful and well-known resources. I guess that's what I've been doing a little bit, during my first few years at the reference desk: as I discover particularly useful or relevant resources I file the shortcut in the back of my mind (or my browser) to pull out later instead of having to redo the search from scratch. But it should be no surprise to find my mental list is far from exhaustive.
In effect I've been creating and maintaining my own collection, and this makes me think librarians are similar to journalists or psychologists: They can rarely be completely objective. They bring their backgrounds and interests and tastes to any interaction with a patron, which is why you'll get different information about subject X from Librarian #1 than from Librarian #2. Ideally #1 and #2 would be interchangeable, because they would both know how to objectively find information about X.
Some of the differences between Librarian #1 and Librarian #2 could have to do with personality, it's true, but I think the more significant factor is the type of collection they've been building internally and what they think of when they hear about X.
Anyone not recently out of library school is probably rolling their eyes at how obvious this is, but it was quite a revelation to me. I guess the idea of every librarian attacking X with the same gusto was reassuring. Maybe it's time to face the fact that librarians are only human :-)