Do you have any idea what percentage is bad?
I noticed in one of our three eight story buildings that all drywall was being ripped out and replaced.
Do you believe that the county building inspectors should know about this as they're 'inspecting?'
At this point nobody knows what makes it "bad," so there is of course no way to test whether a particular piece or batch is bad or not.
The EPA just came out this week with some tests that knock some holes in the previously generally accepted theories of what is causing the problems.