You’ve heard the argument that movie trailers give away too much of the plot, even sometimes giving away key plot twists and the ending. It’s a valid argument.
The last one I recall ruining the movie for me was for Terminator Genisys, which was too bad because that was a decent movie that should have moved the franchise in a new direction.
What a trailer should be, is up to interpretation, but I think you’ll find this one to be lacking any specific plot description or twists. Which is why it’s so perfect. Warning: NSFW language.
Deadpool’s Wet on Wet Teaser: https://www.youtube.com/watch?v=8-Cjsnq8kVU