OK, I know you're going to laugh until your side hurts, but I'm going to throw it out there anyway.....what if you'd really honestly rather not have a movie made of your story unless it's done to certain standards? Obviously, you'll be out some money, and your chances of actually having a movie made will go way, way, WAY down, but will anything else bad happen? If you were my agent, and that happened, would you drop me flat on my ass like the nitwit I am?
Robert Crais refuses to sell movie/tv rights to the Elvis Cole series. I don't think his agent has fired him for that. He did end up writing some stand alones and selling the film rights there, but Elvis remains off the table.
If I had a client who felt so strongly about it they refused to sell rights, I'd have to respect it. I can't sell film rights unless the client agrees....but Miss Snark is damn persuasive when she's wheeling in bales of cash.
What you CANNOT do is sell film rights only to "someone who will not make a hash of it". You can pick the person you sell to, but unless you have an awful lot of juice, you've got zero creative control. Zero. Once you cash the check, you're done.
If you're that worried about quality control, you're better off not selling. What I would can your ass for is selling and then bitching about the results. Whining as you cash the check is not allowed.