Personally I think spoilers are only a problem in a very few instances. Some films(etc) are worth two watches, one blind where you are suprised by the ending and one where you know the ending, and can pick up on al the little things that foreshadow the ending. Momento is a very good example of this. If you have Momento explained before you watch it, ithen your are basically robbed of that first watch. FF7, death note and cowboy bebop are good examples of things that have big 'spoiler' events that, don't really matter if spoiled because the execution of the twist is what I'm wanting to see in a worse case scenario, and best case, I want to experience eveything and the twist is just one aspect of it. Some of you may have heard me talk about School Days, which is basicly a set up and then a reveal. Even though most of the show is a set up for this reveal, and I watched it already knowing what was going to happen.
Nine times out of ten, spoilers don't matter. If you want proof, watch an episode of Columbo. 10 mins in, you will already know who the murder is, and that they will get caught. Even then you will still enjoy the episode.