Mayor Rocky Anderson's committee of booksellers, librarians and city employees bypassed a book involving a pregnant teen (Plainsong) and another about a gay man (The Book of Salt), believing they could cause a squabble. Instead, the panel settled on the Curious Incident, a book about an autistic teen, that wound up causing a stir because of its sometimes-gruff language.

It goes to show you never know what book will offend.

Take it from librarians, who at times hear from irate patrons demanding a particular book be removed. And it's not just because of sexual content or vulgarities, though they make up the bulk of the so-called "challenged" books. Salt Lake City patrons have questioned all types of books - from racy romances to dog-training manuals that suggest swatting pets to a picture book in which cartoon bears weren't wearing pants.

"It's never more than a few [complaints] a year," says Chip Ward, assistant director of Salt Lake City's six libraries. Still, "it's difficult. Librarians are often in that situation of being arbiters of everybody's right to read."

Councilman Eric Jergensen said he didn't want to prevent residents from reading Curious Incident - he didn't request it be removed from the library, where there are 45 people on a waiting list for the title. Instead, he questioned the city's promotion of the book and suggested Anderson's selection committee keep looking.

People who challenge books may not know it, but those titles are celebrated each year. The American Library Association co-sponsors a Banned Books Week (Sept. 25 to Oct. 2). ALA's office receives hundreds of reports a year of challenged materials.

Ward says no challenged books have been removed from Salt Lake City library shelves. The library adheres to standards set by the ALA, which says materials should not be removed "under any legal or extra legal pressure" if the books meet the library system's selection criteria. However, some books in the capital city have been shifted to different sections. Dragon Ball Z, a Japanese cartoon that includes curvaceous characters and some violence was moved from the children's section to the young adult's.

Other recently disputed materials: A book on body piercing because of nude photos; King & King, a juvenile fiction book that deals with homosexuality; "Prospero's Books," an erotic video based on William Shakespeare's The Tempest; "Lord of Illusions," a DVD that involves satanism; and the video "The Cook, The Thief, His Wife & Her Lover," because of graphic violence.

Non-book materials can be the most nettlesome. To keep the director's versions of some movies out of minors' hands, Salt Lake City libraries make patrons request them. Parents whose minor children use Salt Lake County libraries can restrict access to R-rated movies and CDs with explicit language.

In Davis County, librarians removed a book on tape because of its sexually explicit material, but kept the print version of Between Lovers.

Ward says library patrons operate on three assumptions when they question a book's value: They believe others think like they do; they fear the material will harm others; and they confuse the content of a book with the reader's intent. In other words, not everyone who checks out a book on witchcraft intends to practice it.

"When you get 3 million people coming through the library, there's a lot of diversity of thought, opinion and perspective," he says. "We put it out there and people agree to let others read and decide for themselves."