If you watched Planet of the Apes on home video you were already spoiled going in by looking at the cover. That's not something you should spoil yet that's how they did it.
For Psycho, Hitchcock tried with all his might not to spoil the twist, but magazines and articles loved doing it.
The best ones are the ones that people loved spoiling so I always try my best not to do it.
Last finished: Choujikuu Yousai Macross 2036 (Hard-1CC) (TCD), Choujikuu Yousai Macross (NES), Super Dimension Fortress Macross (Arcadia).