Lawrence Turman suggests asking random people for their opinions of your concept. Great idea for a producer, but potentially a bad idea for a screenwriter.
Producers
The One-Month Manager
What’s a reasonable amount of time to give your manager to read a draft of your script? It sometimes takes this screenwriter’s manager up to a month.
How many times can a meeting get pushed?
General meetings aside, how many pushes merits cause for concern regarding interest in you/your idea?
Should a screenwriter pay for notes?
If you can’t find that one smart reader amid your circle, it’s possible that you’d benefit from paying someone. I don’t have any names to recommend, but if I were in your place, I’d look for a few things.