I usually do if I'm trying to decide whether or not to buy a physical copy. Trailers are important. Not only do they get word out that the movie exists, but they help people not waste their money.

I usually don't, especially with newer movies. With newer movies, I feel like I've already watched the movie after watching the trailer. I do like to know the very basic plot and I don't object to images. That, sometimes combined with who directs and who stars is often enough for me to decide if I want to bother with a movie or not.

Most Hollywood movie trailers show way too much, but since Hollywood movies aren't that great these days, it usually doesn't bother me. Trailers for lower budget movies are less common, so it's easier to avoid those (and thus those movies can still surprise you). So basically, I guess I'm 50/50 on it.

No, because they either tell too much or give a wrong image of what the movie is going to be like.

That would be another parameter i dislike about trailers, they can be highly misleading (off the top of my head Goodnight Mommy trailer).

as a general rule no, so many trailers spoil a movie by showing important scenes out of context. Comedies giving away the best jokes is often a culprit of this. Then there's showing a scene from the end of a film, or sometimes a scene that doesn't even make it to the final cut.

obviously they have to market movies somehow, but i like the idea of a short prequel instead of a trailer, like Covenant has done. Gives you a flavour of the film without giving anything away. Or the whole online thing which The Blair Witch Project exploited so well. The Deadpool 2 trailer that was posted on TE awhile back was another example of how to make a good trailer but not spoil the film.

TBP marketing strategy came from the mind of a genius.

i actively avoid trailers anymore, when i can help it. they can't be trusted to properly represent the film and give away far too much of the story far too often.