Successful films start with a strong script. And a strong script makes your life so much easier when putting the project together. Talent will be attracted to it, who will in turn help you to attract the financing, which will lead you to an audience. And really, why would you want to put a lot of time, energy, and money into a poor script?
This is where the development process becomes a very important part of the film's journey. As producer, you may come across a script in which you see the potential for a strong film. It's very likely that the script is not production ready and you will need to take time with the writers and perhaps the director (if you have one on the project already) and help mold and shape the script into something that is sellable, both to talent and money.
As producer, you are the mouthpiece to promoting the film at all phases. You need to believe 100% in the quality of your film. If you are not sure if the script is ready then it isn't. Take the time to make it ready.
Once you believe you have a script ready for talent and financiers, ask others to read it too. Get colleagues and friends who understand screenplay structure to read it. And seriously consider their feedback. It's easy to get too close to a project so get an outside perspective that you respect.
You may even want to send it out anonymously for professional coverage, perhaps to 2 or more readers so you can get a few responses. Studios rely on coverage to weed out the good from the bad. If your coverage comes back and it rates the project as poor, then that is a strong indication that your project is not ready for the next phase.
Remember, material is nucleus! You cannot build a strong, entertaining, sellable product around a weak center. Tootsie Roll is right. It's all about the center!