Marketing titcacs from studios (i.e. trailers, posters, etc.) are totally manipulative and should NEVER be trusted when you decide to see a movie. They are designed to make a film appealing to moviegoers, and even the worst of films can have a great trailer and marketing campaign behind it.Word-of-mouth is okay as long as your friends have a decent tase in movies. But to me, the most reliable source of how good a movie will be is Rotten Tomatoes. It lists the number of positive reviews from film critics and journalists as a percentage, and I tend to see eye-to-eye with critics about what makes a good film. If you don't like film critics, the Internet Movie Database lists reviews and scores of movies from millions of average movie lovers.