Why do TV trailers always look good and feature films are ugly?

Because the trailer needs to leave a lot of suspense to attract the audience, it needs to make the audience feel good after watching the trailer and have the impulse to watch the whole TV series. If the trailer sucks, then people who have seen the trailer don't want to watch the whole movie or TV series. What promotion effect can it have? This is also called marketing. In general, it is to attract people's attention. The purpose of the trailer is to attract the audience. Because the funds of dozens of TV series are limited (as we all know), how much can each episode be divided equally? The trailer is to combine the high special effects of all the plots in just a few minutes. Let us be satisfied. It is also difficult to make a trailer that can be played for a few minutes.