At what point does a movie trailer reveal too much?

I hate it when they show ALL the funny parts in the previews!

All movie trailers do. I would almost prefer to just read a paragraph on a movie than see a trailer.

A preview should show you enough to whet your appetite without destroying the story. It should let you know what kind of movie it is, so you’ll know if it is your taste.
City of Men comes to mind as a preview that completely ruined the movie. Plot twists, and the huge finale were all revealed. I loved that movie, but I felt cheated of the thrill of discovery.

It always seems to me, they show the best parts of the movie in the trailer. Then when I see the whole film, it is an anticlimax and leaves me disappointed because the rest of the content dims in comparison to the really good bits in the preview!

When it reveals too much of the movie plot, best scenes, and funny parts which in turn ruins your viewing experience.

Definitely when all the best scenes are in it. I even saw a movie trailer recently that showed the last scene of the movie—but way out of order. That’s just plain misrepresentation as well as a spoiler. The trailer was way better than the movie!

most times they do

What really drives me crazy is when there is a great or funny scene in a trailer, and it doesn’t make it into the movie. You expect it, that moment comes, and it’s a lesser take!
Spiderman, Ironman, Tropic Thunder have all done this.

I dont watch Trailers anymore for this reason.

I hate it when all the funny parts are shown and they are the only good parts of the movie.
I also hate it when the trailer makes a movie look like it is a comedy and it really isn’t.