I thought that while the elevator blood shot may be arbitrary in the film (though it is a rather powerful shot that fits with the grand intensity of the film's climax) as a stand-alone trailer it's rather genius. It's a powerful enough shot that doesn't give away what happens in the film and also invites the audience to run wild with intrigue.
I think the "Little Children" trailer is a fantastic example of showcasing the mood of the film without giving away what exactly it's about (only a subplot of the film is explained). Though the makers of that trailer probably designed the trailer as such so as to avoid the Jackie Earl Haley character and his story, without being condemned by selling a false bill of goods.
Speaking of "The Shining" trailer mash-ups (though not as cool as "Shining")... http://www.youtube.com/watch?v=j4iAJ2EAdTY
Earlier this summer M. Night might have made yet another $100 million grossing shitty movie but the summer ended with his name being laughed at off the screen during the "Devil" trailer. The audience reaction trailers might have been taken down from youtube but they live on before showings of "Scott Pilgrim". So fear not: the shitty aspects have a way of being evened out. I consider this summer a break-even.
Brilliant! And "Stephen Tobolowsky's Birthday Party" is a must see for those who love his stories.