I've never really understood why people get so worried about 'spoiler alerts.' Maybe it's a result of reading so much, watching so many movies, and just generally following so many stories, but I haven't been genuinely surprised by any bit of media, be it movie or book or TV show, in ages. That doesn't mean I always accurately predict where something will go, but I haven't encountered anything new and shocking, that's for sure. My reaction to plot twists is usually "Oh, so they went that way with it."
Besides, we don't watch and read things for the plot twists. That is only one tiny part of the deal. Even a movie like the Sixth Sense, where so many people were worried about spoiling the ending for those who hadn't seen it, wasn't ruined by knowing the ending beforehand (which I did, do to my tendency to eavesdrop) - it wasn't even particularly harmed. So what if I knew the guy was a ghost? I can still enjoy the story, and observe/admire the storytelling. I basically just skip ahead to my second watch, where I look for all the tricks they use to keep the secret without making it obvious.
That being said, I do tend to avoid reading reviews or watching trailers for movies - I've avoided learning much about the Hobbit - but that is because they DO reveal something I want to wait for. The visuals, the spoken lines, the little things behind bringing fantasy to life. The more I learn about things like that the less I can sink into the fantasy. I want at least one viewing unadulterated with the minutiae of what the cast might have been doing before/during/after a particular scene.