Probably "Snape kills Dumbledore" which was spoiled by some jackass trolling the chat box of an online game. 
Not a huge deal I guess since I only watch the movies but still pretty annoying.
Technically you're right, it's not true. But ...

Not a huge deal I guess since I only watch the movies but still pretty annoying.
I have never watched Lost but due to its popularity and constant mention on internet sites I know thatthey are all dead and everything that happens on the show takes place in Purgatory.
Not true.
Although it was funny listening to Jason Smith on ESPN radio complaining about the ending of Lost even though he didn't watch it and was strictly going off the incorrect articles online.
Technically you're right, it's not true. But ...
The show does end in a kind of purgatory, but the events that happen earlier in the series do not take place in purgatory. I kind of view it as the producers "having their cake and eating it too". But then I didn't like the ending.