I haven't read the books, so after last season, a friend who is a book-reader told me "I'm so looking forward to next season", I told him to shut up and not say anything, but he had to add "Of course, but you know the wedding between Robb and Talisa? Not good". I knew Robb had broken an oath, I knew it would have bad consequences in some form or another, but once he points out that specific event out off all other events that could have bad consequences, I knew right away death would be involved (that's how GoT rolls). It was more brutal than I thought though, didn't think both Robb AND Cat would die. Book readers don't really have bad intentions, they are excited, but just pointing one thing out gives it importance and spoils some of the impact.