I found this quote from President Ezra Taft Benson when he was president of the Quorum of the Twelve Apostles:
"Today, with the abundance of books available, it is the mark of a truly educated man to know what not to read...
"Feed only on the best...
"As John Wesley's mother counseled him: 'Avoid whatever weakens your reason, impairs the tenderness of your conscience, obscures your sense of God, takes off your relish for spiritual things, increases the authority of the body over the mind.'"
In other words, ask yourself, "Do I feel like reading my scriptures and praying right after this book, movie, TV show, song....?" Not that we always need to be spiritually minded (or do we?), but these things should make us feel like doing good things afterwards.