Movies that change their ending for effect...Thoughts?

[The Shroud]

What do you guys think about movies that re-write the movie at the end? I've seen some horror and thriller movies that were actually good films, but then in the last 20 (or even 5) minutes of the movie they either basically tell you that nothing that you've been watching happened, or that it happened differently than what they showed (even to the point of being impossible). Sometimes, I think it was just a way to have a surprising twist at the end, but sometimes I think it's just weak writing and a general desire (but lack of ability) to write a mystery. These changes can either wind up not making sense, or create way too many questions that get left unanswered, since they are trying to spend 5 minutes retelling the last 85 minutes of film and then roll credits.

[Dead Bad Things]

I'm just in it fer the rush...fer me most times if the story line creates enough horripilation, terror, and chaos, I don't care so much about the end plot. It doesn't have to make sense how it ends s'long as it was a good ride. Bentley Little fer example..

[Ferox13]

I think Haute Tension gets a lot of hate for this but I am always pretty fond of the unreliable narrator device...It annoys me more in the it was all a dream/they are already dead scenarios, Mostly as it is so overdone and lazy.

Not a horror film but a great twist on the unreliable narrator device is '300'.