That’s a good question, and I didn’t mean to make anyone feel bad for spoilering their posts, since I know you’re all doing it out of thoughtfulness!
I don’t think there’s any agreed convention, but it seems to me selective spoilering is appropriate for something like a TV show, where people’s viewing habits vary, so what is and isn’t a spoiler will be staggered among various tiers of people in the discussion. In those situations, I sort of understand the “heavily redacted document” look. But for me personally, if I’m in a thread reading a discussion about a movie or TV show, it’s almost always because I’ve seen the whole thing.
But again, that’s just me and I know a lot of you are perfectly happy skimming threads for movies you haven’t seen. So for you guys, those selective spoilers are probably very helpful. But I tend to just post either with spoilers or without, and if it’s with spoilers and it might not be obvious from the context in the discussion, I’ll just label is as such at the top of the post, and then blather freely from then on. Like here. And it seems if someone does that loudly enough, it sets the tone for the rest of the thread?
So, again, I wasn’t try to make anyone feel bad for spoilering their posts. Just grousing about my own personal opinion. :)