I'm an optimist; I always hope that each new script is going to be a great story.
In my opinion, the vast majority of scripts written - as well as most movies that are released - are not very original, well-written, or interesting. It has always been that way, and I think it always will be.
It's very rare you get a great script just handed to you, or sent to you, by someone you don't know.
This basic thing I always do: 'What happened between the character's birth, and page one of the script?' Anything that's not in the story, I'll fill in the blanks.