I find promos for new episodes of TV shows quite irritating. They're so manipulative. And it's not just how they arrange bits of scenes together. Sometimes they will actually use an entirely different take for a clip in the promo than what we actually see in the episode once it airs.
Tonight's episode of Elementary is an example. It's subtle yet it manipulates the way you see things. In the promo it has Sherlock saying "This means war" in a rather forceful way. It turns out he was simply translating something written in another language. And when he says it in the episode it is said with far less vehemence.
A few years ago when Eureka was still on I was very disappointed when a scene in a promo did not turn out the same way in the episode. There was a different line in final cut. I thought it was funnier the way it happened in the promo.