O.K. So the answer to this might be obvious to some people. But probably not for others. Why should movie trailers be avoided?
There's clearly no objective answer. Some people might say that movie trailers shouldn't be avoided at all. And that's fine. However, I believe in the opposite.
Here's the main problem with a trailer: it takes away from the film. In other words, you somewhat know what to expect. And when a scene from the trailer plays, the stakes aren't as high (assuming that you've seen the trailer). And when the stakes aren't as high, your emotional response is lowered.
I guess what I'm trying to get at here is that seeing a movie trailer before the actual movie itself hurts the overall experience.
And sometimes the trailer is generous enough to provide you with the whole movie in a TL;DW fashion. Now, this is good if the movie isn't worth your time or money. But if you actually want to see the film, you will be pretty much watching a longer version of the trailer. And, for the most part, you know what to expect.
Why Trailers Are Hard To Avoid
Now, it's nearly impossible to avoid movie trailers these days.
Whether we like it or not, we live in a world full of advertisements. Movie ads play on T.V. constantly. We see them on the sides of our browser windows if we don't have an ad blocker enabled.
Now, you could probably just argue that you could not watch any T.V. (at least during the commercials) and keep an ad blocker enabled at all times. However, you have to remember that movie theaters themselves advertise movies. And I don't blame movie theaters for this. They need to make money.
If you don't want to see a trailer but want to see a movie, then you would have to either not pay attention to the first 20 minutes or just walk into the theater later on. Though, if you do the latter you may end up with a bad seat.
Or you could watch the movie online from your home.
It may seem like a huge headache just to avoid watching the trailer to a movie you really want to see. Most of the time I can watch a movie without having to go to great extents to avoid seeing the trailer (especially if the film is older or not as well known).
In all, it's probably best to try to not see a trailer purposely. If you happen to see it, don't sweat it. There's a good chance that you won't remember what happens.