Interesting topic.
I can copy what Andy or Dyland wrote.
Usually I grade trailers and teasers more like commercials, too. So more contrast and especially brighter.
Mostly the customers want the trailer during or at the end of the feature film grading. Sometimes upfront if they are going to film marketes and try to sell the film. Then I push it even more towards a commercial.
If during the grading, then I copy the already finished looks but it could be, that I totally change the grade.
It also depends on the edit and how they assemble the shots. The looks from the movie sometimes don't work with different edits.
So in some cases the trailer grade comes out very different from the movie.
A trailer is a commercial for the film, so it needs the character of the film, but at the same time has to stand out and attract. It also depends on how fast the edit is. The faster, the less time for the eyes to adjust and so I am masking more and try to guide the viewer - like a commercial.
cheers