I feel your pain. Our inspector was not physically able to access the crawlspace in the attic. After moving in and our first big rain, I went in the attic and noticed numerous leaks (30 year old monier tile w/o subroof). With the obvious rot and water stains, it didn't take a roofer to notice there was a problem. We look at the inspection report and wouldn't you know it, there are disclaimers all over for each section of the inspection. Why do we hire these people?
$13k lesson. Papa always said, "just make sure the roof don't leak," and I failed.
Sorry, had to rant...