Films ruin novels

Is it Just me or do other people notice that when book become a movie it is always worse than the original text. It just seems that every time a hollywood studio adapts a book it ends up being a cinematic disaster. I have such a hard time understanding how people with multi-million dollar budgets fail to complete such a simple task. I think part of the loss fall within set creation and background information. Half of the charm of a well written novel is the way the author can paint the scene with words like silk. What do other people think?