There used to be an Index of Forbidden Books. It was effectively abolished in 1966 by Pope Paul VI. Wiki has a link to the Index that was current in 1948. I scrolled down it (it is huge,) and most of the works seemed to be philosophic, theologic, scientific, or political tomes, not works of popular fiction. Also, the list seems to be in Italian.
The Wiki article indicates a couple of interesting things: Adolph Hitler’s Mein Kampf was never on the Index, but for awhile, St. Faustina Kozlowska’s writings were. I’m not sure how accurate Wikipedia is, since it can at least be theoretically edited by anyone at any time, but those notes struck me as pretty odd.
The Index listed books that were considered dangerous to faith and morals for Catholics to read. What did emerge, as the film industry grew, was the old Legion of Decency, which turned into the National Catholic Office of Motion Pictures. As I recall, they were the first to institute a rating system of movie content, and new releases frequently were mentioned in my diocese’s monthly newspaper, along with the film’s rating. One of the ratings was “C”–for “condemned,” which loosely corresponds to the current “X” rating. The movie industry caught on to the idea and developed the current rating system from the NCOMP system and adopted it as their own policing system (as marginally effective as it is.)
I do recall that occasionally, a book that was particularly smutty or anti-faith would get reviewed briefly in the diocesan paper, and Catholics were warned not to read it. Being the 1970’s at the time, I’m afraid that a lot of people took that as a review that a book was particularly enticing, and bought it anyways.
For what it’s worth, #s 1, 5, 6, and 9 were on my parochial school’s seventh grade summer reading list in the early seventies. And we were expected to write book reports over the summer on them, and hand in the book reports on the first day of school. Doing otherwise would have invited the wrath of Sister Mary Joan!
Also, for what it’s worth, I was one of those Catholics who didn’t resist, and read “DaVinci Code.” I confessed it afterwards, and the priest said that wading through that over-hyped trashy sophomoric waste of paper was penance enough!