According to many critics, Hawthorne should have been less friendly toward his main character, Hester Prynne (in fairness, so should have minister Arthur Dimmesdale). One isn’t surprised by the moralist outrage the book caused in 1852. But when, one hundred and forty years later, the book is still being banned because it is sinful and conflicts with community values, you have to raise your eyebrows. Parents in one school district called the book “pornographic and obscene” in 1977. Clearly this was before the days of the World Wide Web
It's hard to imagine anyone wanting to ban this book, but according to 120 Banned Books: Censorship Histories of World Literature by Nicholas J. Karolides, Margaret Bald, and Dawn B. Sova (published by Checkmark Books, copyright 2005, pgs. 480-481), people have:
The novel was a success when it was first published, selling out a first printing within a few days. Although critics and literary figures praised the novel, religious journals and clergymen denonced it as “a dirty story” that belonged only in “a Brothel Library.” A review in Brownson’s Quarterly declared that neither Dimmesdale nor Hester exhibited “remorse” or “really repents of the criminal deed” and that “it is a story that should not have been told.” In Church Review, Rev. Arthur C. Coxe also condemned the two main characters as not being sufficiently repentant and stated that “the nauseous amour” was not appropriate subject matter for fiction. In 1852 Coxe called for the banning of The Scarlet Letter as he launched a savage attack, proclaiming that he was against “any toleration to a popular and gifted writer when he perpetrates bad morals – let his brokerage of lust be put down at the very beginning.” He stated that he could not tolerate a novel that dealt with an “illicit relationship.”...The citizens of Salem were so incensed by Hawthorne’s novel that he moved his family out of the city to a farmhouse in the Berkshires.
...In 1961, parents of students in Michigan objected to the assignment of the novel in high school English classes, claiming tht it was “pornographic and obscene.” They demanded that the book be taken out of the curriculum, but the request was denied. ...In 1977, a parent in Michigan objected to the inclusion of the novel in the high school English curriculum because it dealt with a clergyman’s “involvement in fornication.” The book was removed from classroom use and from the recommended reading list. That same year, a parent in Missouri condemned the book for its use of “4-letter words” and “other undesirable content” and demanded its removal from the high school library. The school librarian recognized that the parent had not read the book because no obscenities appeared in the novel, and she convinced the parent of his error. The book was retained.
In a 1982 survey of English department chairpersons in Ohio, James Davis reported one challenge to the novel in which a parent claimed that the book was about “adultery,” a “Womanizing preacher” and “prostitution” and requested its removal as an assigned reading in a high school English class. The school board denied the request.