A TriggerStreet poster recently asked at what point should he approach a producer. This was my response:
Wait until it's finished -- and polished (which means about 10 drafts in) before you start shopping it.
(1) If it's a great high concept you risk someone -- 'hey let me tell you about this great idea -- but the script sucks -- but listen to this!" -- hearing the idea. And using it.
(2) If they read a first/early draft and it sucks, you're out the door and the door is closed. Don't care what anyone else says on here, people in the industry (real production companies that is) work this way. They cover the script and you as a writer. If you score PASS as a writer = door closed.
BTW, early drafts always suck. Saying "I'm almost finished with this script" means "I'm about to waste your time." You want "Written and rewritten, it's polished and ready to shoot next week."
(3) The script isn't written yet and how can you pitch it if you don't know the story? You may be pitching something that's a cute concept but won't work on the page.
(4) Short term memory in Hollywood. From "I've got this script" to getting it on their desk -- maybe two weeks; usually one; usually the next day. So many things flying at them if you catch their attention you want to be ready to roll.
That post addressed this common question.
BTW, I currently have a contact to an A-list producer that would be ideal for one of my scripts. About a dozen drafts in it's still not ready. Getting notes on it form Erik Bork (Emmy winner for BAND OF BROTHERS who posted his services on DoneDealPro) and making sure it's in 'ready to film next week' shape. Producer of an Oscar-winning film.
90% plus (if you talk to people who judge screenwriting competitions it's higher than that) of the material floating around in the system should be floating somewhere else. It's not ready. May be a decent idea there or great potential but it's not executed at a professional level.
Now, Hollywood may be forgiving a bit if the script is a high concept they love. The execution can be improved by the screenwriter or someone they bring in to rewrite it (which happens often) but the concept can never be improved. This is why it is so critical to spend your precious writing time working on scripts that have a chance of getting you in the game.