I’m mostly indifferent towards spoilers. I don’t watch many tv shows as they’re airing, but I love adding things to my queue after reading reviews. I also listen to a few podcasts that cover movies and shows, and I’ll frequently start something that has already been spoiled because it sounds interesting.
Offering unsolicited spoilers is straight up jerk behavior but self-spoiled material is still enjoyable. Audiences are frequently familiar with the source material before watching content and it’s still enjoyable if the material is well adapted.
Game of Thrones S1 didn’t feel like it came out of nowhere to me but when I went back and read the first book, I finally had a better understanding of why people were so surprised by it. The S3 twist absolutely floored me though. Definitely didn’t see that coming. I self-spoiled for the rest of GOT after I did a pretty deep dive in their wiki and indulged in several podcasts that were designed with book readers in mind.
@MaxTheVool is onto something with the tiers. Whodunnits are at the top of my list for spoilers that affect my engagement with the material. So much of the story is dependent on the big reveal that it can significantly diminish my enjoyment. Horror movie reveals are a close second for me but I feel like some of those could be considered mystery/whodunnits.
The Good Place would’ve been a very different viewing experience if I knew the reveal ahead of time, but I disagree with people who insist that it doesn’t hold up on rewatch. I’ve rewatched a few times and it’s been an absolute pleasure each time.
I’ve noticed that other posters have given several examples where the spoiler was common knowledge by the time I got around to watching the movie and I still enjoyed myself. As @Briny_Deep mentioned, there is definitely a statute of limitations. I was born in ‘84 so most movies that came out before ‘95 were pre-spoiled for me and I didn’t really have an issue with it.
Citizen Kane, Empire Strikes Back, and The Usual Suspects were all spoiled for me before my first viewing. Admittedly, the way The Usual Suspects was spoiled wasn’t super clear to me so it didn’t really click until the reveal anyway.
Citizen Kane’s spoiler didn’t ruin anything for me. I was preoccupied with the journey and the style and techniques that were being used to tell the story.
For Empire Strikes Back I was focused on how the characters responded to the reveal and it blew me away as a kid. It almost felt like reading a story where you know something the main character doesn’t and you’re just building towards that reveal to see how the protagonist reacts.