When I went to Waterstones the other day, I stared at the twin categories Crime, vs. True Crime. Placed side by side, they hold an interesting dialogue with each other: do crime story authors, detectives and investigation officers like to read true crime for inspiration?
There is also another intriguing and sad category called Painful Lives. This category occupies a shelf of its own. I suppose the bookstore would need some internal guidelines to help staff find out what books to put under this category. After all, it can be a rather subjective interpretation.
At the Norwich Millennium library, they dedicate an entire section called UFO. A brief desktop research reveals repeated sightings and strange lights reported for the mysterious wide-open skies of East Anglia. I don’t think it is a typical book section for any library. (Ref: http://www.nationalarchives.gov.uk/releases/2008/october/ufo.htm)
Next time you visit a bookstore or library, check out the way they organise the collections.