Speaking for myself, well, yeah. To both parts of the question. With certain stories, be they written or enacted, there is one defining moment that, when you know it, unlocks the rest of the plot. Or explains it. And that shock you get the first time you see it is what makes it so much fun.
Let’s take, as an example, Miracle Mile. The movie builds tension, never letting the audience know what the true story is, until the final reel. Once you know how the flick ends, it knocks a lot of the enjoyment out of the flick, for repeated viewings. Well, it did for me, anyway. I’m one of those people who does rewatch the hell out a lot of movies, and can enjoy them even knowing the ending… but with certain stories, the first time you watch it is the best.
There’s a subset of stories who fall into the “Twilight Zone” category, in that they contain a ‘twist’ ending, which is almost always the big pay-off to the thing. Once you know that, again, generally speaking, repeated viewings/readings of it are a lot less enjoyable, as a great deal of tension is bled out the plot. Think of the classic Burgess Meredith librarian espisode of TZ; is the ending as wrenching now as the first time you saw it? (Assuming that you have seen it, of course.) This holds true for mysteries, murder or otherwise, as well.
Of course, I’m the kinda guy who’ll tape a Columbo movie (y’know, Peter Falk) I haven’t managed to see before, and intentionally skip the first 15 minutes or so, the first time I watch it; my perspective on the matter may therefore be a little… skewed.
And yeah, maybe a certain time limit on revealing spoilers could work out, but…
What about the young movie lover who is only now discovering some flick or another, that us old farts consider too old to spoil? Pick some novel/movie/campfire story that you really loved. Now imagine that you were born 10 years later than you actually were: Someone gives away the spoiler to you before you’ve had a chance to enjoy it for the first time, as the author/director intended. Is it as much fun, now, or just another movie you don’t really feel like going through the effort of tracking down, since you already know how it’s gonna turn out?
Yeah, I know, it’s just a movie an’ alla that, but… I like being surprised by the occasional plot twist. The ones that work are rare enough as it is.
[sub]It is a good idea to stay away from threads discussing a flick you wanna see. MsWhatsit nailed it pretty succinctly, I think.[/sub]