This piece of interview with Roger Corman on Joe Dante's work on trailers is my fawourite:

"Were there any elements that you had to tell Dante to tone down?

Not really. There was one memorable moment when Joe showed me a trailer for a picture just before lunch. I said, “Joe, it’s alright, but it isn’t quite as exciting as I would like it to be.” He said, “Let me work on it through lunch.” I came back after lunch, and it was exactly the same trailer, trimmed a little bit, with an exploding helicopter. I said, “Joe, that’s an exploding helicopter from a war picture we shot in the Philippines!” He said, “Well, don’t you think it helps the trailer?” It did. It was great. And I thought about it for a little while, and I figured, there’s no law that says every scene in a trailer has to be in the picture. So we left it in. After that, whenever Joe had a dull moment in a trailer, he would add the exploding helicopter."

Src, full interview