The other day, another writer posed a great question: "I always wondered if it pisses authors off when a movie is made from their work, but it sucks...", and it started a discussion about selling your stories off to be turned into film without keeping any creative control. This was interesting to me because I have already been approached twice by people that I have turned down due to the changes they wanted to make to the source material.
Does that mean I will never sell one off to be made? Not at all. In fact I look forward to the day when I can, even if I have to give up most of the control of it. With the prior two, it wasn't just that they wanted to change character names, how the story played out, or in one case change the title, it was also that they wanted me to "donate" the stories to them. That's where I draw the line. Without trying to be too vulgar, if you are going to try to fuck me, at least pay for dinner.
So the next question is, if a story of mine was turned into a terrible movie, would I be pissed? Yes and no. Of course I would want a great movie to be made of something I wrote, but in horror, sometimes terrible is better. I would take Killer Klowns from Outer Space over The Ring any day. I grew up watching terrible movies, I own close to 500 of them right now and am always looking to add more to my collection. Terrible movies are the backbone of horror. They become cult classics and that would be awesome in my opinion. Better a terrible movie be made that people talk about, than a mediocre one they quickly forget.
In the end, the way I see it is this; having a movie made of one of my stories, good or bad, just opens up the possibility of getting a few more readers. No matter what the movie is like, the source material will always be there for people to find. And if it is a bad movie, at least people will be able to say "the book was so much better than the movie", and that is fine by me.