Let me back up a minute and give you some context. I'm interning at the county jail library this summer and fall. Well, "library" would be more accurate because it's a room of over ten-thousand books thrown together without organization. Staff members have kept some very popular authors and series set aside, but any inmate requests outside of those are unlikely to be filled. There's no way to locate or even confirm the existence of those items. My job is to do a lot of the grunt work in turning this pile into a collection.
Inmates can request a particular title, author, or genre. They won't be able to browse the shelves directly. I knew that if I had a big "General Fiction" category, not many people are going to write: "Please find me some General Fiction novels!" How utterly boring! Might as well throw out every less popular author in that entire section.
I needed to come up with enough genres to put an interesting genre label on everything, even titles not traditionally considered "genre fiction." After much agonizing, I came up with the following scheme:
A cheating category. Classics are, roughly, pre-20th century books that are still reprinted or re-translated. Sherlock Holmes and Dracula would fit, but they are so strongly expected in other genres that they don't count.
Traditional "Genre Fiction"
Sure, these can be separate, but readership and the works themselves very frequently cross over. Plus, that's a rockin' dragon sticker. What goes here? Advanced technology, strange worlds, and supernatural things that most people agree aren't real.
Anything explicitly labeled "romance" or from a romance imprint goes here, even if it has strong SF/Fantasy elements. Also included are books with descriptions that exclusively describe a romantic relationship, i.e. not just as a major element in a story focused on another kind of struggle. It's no accident that I picked a non-gendered sticker.
Like romance, westerns are predominately identified by their marketing. Although there are many titles that mix romance and western themes, it's usually easy to tell romantic westerns from western romances. Unfortunately, this distinction tends to line up with marketing to men vs. marketing to women. This is one way that genre labels stifle discovery by exaggerating the separation between quite similar works.
Some mysteries are labeled as such, but it makes sense to be more inclusive than that. Whenever the plot centers on discovering the identity of a criminal, it's a mystery. SF/Fantasy mysteries still get dragon stickers.
General Fiction and Literature
With "genre fiction" out of the way, what can be done about the great big Miscellaneous category found in most bookstores and libraries? I broke it down into three parts...
An arbitrary but popular line to draw is that fiction set during or before the World Wars counts as historical fiction. Unless it fits western conventions, or those for SF/Fantasy, or mysteries. Even with all of these exclusions, these shelves are bursting.
Thrillers is the section for spies, soldiers, and serial killers. Film versions of thriller books go under Action/Adventure. Crime fiction can go here if the reader finds out the antagonist's identity early on and the big question is whether the protagonist can do something about it.
Technically, thrillers tend to be realistic in the sense that they are contemporary stories without fantasy or science fiction elements. Realistic fiction concerns relatively regular people in relatively common life situations, though not necessarily from the reader's own culture. Film versions of these books tend to go under Drama. Elements of romance, thriller, and mystery genres can be present, so long as they don't overwhelm the focus on complex contemporary characters.
It might be OK for Barnes & Noble to have a Christian Fiction section, but it doesn't sit so well with librarians because it can imply that the other fiction either is less suitable for Christians to read or is insufficiently orthodox. State librarians are not in the position to issue or promote religious imprimaturs. Plus, it pulls books away from from all of the other genre shelves where they might find a broader readership. The Chronicles of Narnia, Left Behind, and Seasons of Grace are much more at home in SF/Fantasy, Thrillers, and Realistic Fiction respectively.
That said, some readers are publishers and readers who favor books with strong religious themes. Other readers feel strongly about avoiding books from such publishers, either from religious disagreement or for the same reason a person who likes romantic fiction might distrust the quality standards of "romance mill" publishers. So, in addition to a primary genre sticker, books from such publishers or imprints (e.g. Harlequin's Heartsong) will have an "Inspirational" label:
Not the most apt term, but it's a widely-understood convention that further distances librarians from the legal and ethical issues of judging some works to be "Christian Fiction."
Easy and Limiting
The single best article I've read on fiction genres is Ursula K. LeGuin's "Genre: A Word Only a Frenchman Could Love" (Public Libraries, Vol. 44, Is. 1, p. 21 [PDF]). I recommend reading the whole thing. LeGuin would prefer a world where all fiction is interfiled by author's last name, removing the prejudice of genre systems. But she knows her vision would be opposed:
"Consumerism also rules. If the books aren’t labeled, if they aren’t shelved by genre, if they don’t have a little bitty label saying SF or M or YA, a whole lot of customers and library users will come storming the counter or the desk, shouting, 'Where is my fiction fix? I want a fantasy, I can’t read all that realistic stuff! I want a mystery, I can’t read all that plotless stuff! I want a masterpiece of grim realism, I can’t read all that imaginary stuff! I want mindless fluff, I can’t read all that literary stuff! Etc., etc.'For my particular situation of no-browsing-allowed, sticking out a hand (so to speak) is the best supported scenario for discovering new books. Can public and school libraries do better? I'm having trouble finding references right now, but I've heard of libraries interfiling all fiction and using small, colored genre dots on the spines. The nice thing is that there's no need to pick a "primary" genre, so those readers of western romances and romantic westerns are more likely to notice similarly-themed works and go exploring outside of their traditional haunts. Heck, I've seen things like inspirational-historical fiction-romance and SF-mystery-thriller. These books could easily be picking up new readers through providing more genre information than traditional genre shelving supports.
To give each reader an annotated author-title list of whatever their fiction addiction is, so they can go find the books on the shelves, is a perfectly fair solution, offered by many libraries. But addicts don’t like it. They want books to be easy the way fast food is easy. They want to go to the shelf and stick out their hand and get a fix."
Library catalogs could also help, but usable catalogs are still the stuff of science fiction. For now, physical genre markers are still the best way of directing many people to titles they'll feel comfortable trying out.