They have slick soundtracks, all the funniest jokes and show the best of the action scenes, so fans watch them religiously to try and pick up any nugget of information before the movie is released.
And while they serve their purpose of getting the viewer primed before the release date, it can give away a whole lot of what happens in the film, so by the time you actually get into the cinema, there will be very little left to surprise you.
So if you are thinking of seeing Thor: Ragnarok, which you should anyway because it’s absolutely fantastic, try and avoid the trailer if you haven’t already seen it.
Not that it would ruin your experience, because the movie is truly amazing, but not being aware of what it has in store for you may increase your enjoyment.
Ragnarok takes everything that you enjoy about the Marvel Universe - the funny one-liners, zany characters and fun action sequences, and makes it feel fresh and new, which is saying something as this franchise is in its 10th year.
The film follows Thor (Chris Hemsworth), who is defeated by the evil Hela (Cate Blanchett), and ends up in a foreign world named Sakaar.
Thor knows that he must travel back to his home world of Asgard, as there is no one left to protect it from Hela, and prevent Ragnarok.
Before he can do that, he is captured by the planets elites and forced to fight in the gladiatorial ‘Contest of Champions’ against the mysterious Sakaar champion.
As he can occasionally get lost among the shuffle in the Avengers films, Hemsworth once again shows how perfect a match he is for Thor.
While he could coast along on the looks alone, he delivers another knock out performance with his comedic timing and physicality, as well as the heartfelt moment that feels truly earned.
It makes it difficult to think of him as anyone but Thor now, and he really makes the case that he is the standout Avenger.
As with every Thor movie, there is a heavy dose of his brother Loki (Tom Hiddleston), who again feels very comfortable in a familiar role.
One of the new characters who also stands out is Valkyrie (Tessa Thompson), a hard warrior with an even harder drinking problem, who brings a slightly different edge to the movie.
And because it is directed by acclaimed New Zealander Taika Waititi, it mixes in some truly great Kiwi humour that you obviously don’t often see in big Hollywood movies.
If you are a Marvel fan, you will love this movie, and may even regard it as the best one they’ve made.
If you aren’t however, this is a movie that you can still enjoy, due to the strong humour and the (mostly) well written characters.
But you will see recurring problems that have plagued former Marvel films, as this effort is by no means perfect.
While Blanchett gives a menacing performance as Hela, she does seem like just another disposable villain. This is made even more glaring in the third act of the movie, which can at times feel like a rerun of previous superhero movies.
Some of the characters or references might also go over your head if you have not seen many of the previous films.
But ultimately this movie succeeds because it knows what it is and what the audience enjoys. It delivers strong performances from the charismatic cast, and is infinitely improved by the cheeky New Zealand humour.
Just try and avoid the trailer if you can.