I've always demanded spoilers for what I watch, but I understand that most people like to go into films unspoiled. It's odd then, that the curse of knowledge makes spoilers for the most important films of our time unavoidable.
The "curse of knowledge" is pretty well known. People who have some piece of knowledge, whether it's technical or incidental, have a hard time thinking from the point of view of people who don't have the same knowledge. The principle is especially difficult for children. Before they've reached a certain stage of development, it never even occurs to children that, if they know something, the people around them don't share the same knowledge.
Adults are a little more rational, but they do the same thing. People in technical professions rattle off details and acronyms that no one knows, assuming their audience is following along. Looking back on an incident that went wrong, most people sincerely believe they would have made the call that would have turned the situation around. Everyone has a friend who, when doing updates on their life, will say things like, "Jason and Clark are getting a new set of keys because of what Amanda did in Boca Raton," and expect an informed reaction.
Then there are the pieces of knowledge that "everyone knows," and so everyone talks about. I had Darth Vader's famous declaration spoiled for me before I'd ever heard of Star Wars. Cartoons, comics, even news readers would do the Darth breathing sounds and declare "Luke, I am your father," whenever the opportunity presented itself. Reign of Fire, the otherwise execrable dragon movie, has one great scene. Its adult characters re-enact the scene from Star Wars for a truly shocked crowd of children. It's only in a post-apocalyptic, post-industrial world, where there is no electricity, few books, and relatively few older people, that any kids will grow up not knowing about Luke Skywalker's family tree.
In this world, they will always know about Luke n' Darth, just like they'll know what Rosebud is, and who Ingrid Bergman will run off with in Casablanca. This is where the curse of knowledge gets a dash of irony. The more important, iconic, and timeless the film is - the more likely it is to be spoiled. There's no point in referencing a film that no one knows. Any skit or play that references currently popular but forgettable films is forgotten along with those films.
I like my movies thoroughly spoiled. In making references I try to give a decent amount of time to a movie before I spoil it. Personally, I think if you add up all the great references and spoofs about a movie, they're worth the fact that some people won't get to see it fresh. Still, there's an irony to fact that spoilers are ubiquitous only for the most important films. The best films out there - the ones that would be most breathtaking for people to see without being spoiled - are the ones that are most likely to be spoiled.