The case of Spoilerism is one in particular that deals with an undeclared cut off date at which people can freely discuss an 'older media'. For example after something has reached the point at which it is on DVD and available at all local libraries.
The more conservative spoilerist is angered by this, and considers the entire act one of terrorism, in which the show or movie is now ruined essentially and not worth watching at all now. Particularly common among enraged fanboys etc.
Most people can distinguish between the easy non-spoiler such as Titanic or Snakes on a Plane. But even in this case the spoiler sensitive may take offense.