The job of the people who make trailers is not to convey the real quality of a movie. It is to get you to buy tickets. io9 has a funny and astute primer on how to spot tricks in a trailer that make the movie look like it’s worth seeing, even when it isn’t. Two of my favorites:
Dog Reaction Shots
If they have to show you a dog’s reaction to the events that are happening on screen, that’s probably a pretty bad sign. They don’t think you’ll know how to react without a dog letting you know.
A pretty woman does an over-the-top pratfall
This is mostly in romantic comedies, but also in other types of films. Comedian Emily Heller describes this one thusly: “Whoooaaaa! She’s clumsy! She has a FLAW! She falls down! That’s the only thing wrong with her though because otherwise she’s a 10.”