According to some Building Departments they only inspect the plywood on new construction. They do not inspect it on existing structures. The inspections often consist of checking the felt, flashings and drip edge. The final inspection is to make sure the correct number of fasteners have been used to hold the shingles in place.

Question...

Does it really matter if the correct number of fasteners are used if those fasteners are attached to badly rotted wood - similar to Swiss cheese or butter?

I explained to our local Building Department that we had obtained a building permit and underwent not one but two inspections. I asked, "How did that protect me?" Their response was, "It didn't."

Roof Truss, Bracing, and Sheathing Inspection: to be made after placement of panels or planking and prior to application of base or anchor coat of roofing. 

 Exception: Sheathing, not to exceed 200 sq. ft. and replaced in the course of re-roofing, does not need to be inspected as part of the mandatory inspection.

http://www.melbourneflorida.org/code/preinspection.htm

Some Don't And Some Do

Roof Replacement

1. In Progress Inspection: To be requested in anticipation of the tear-off of the existing roofing and shall at a minimum include the following:

Roof sheathing

Roof dry-in

Flashings

Drip Edge

No roof coverings shall be installed until until progress inspection is approved

Tarpon Springs

Q How come my roof passed inspection and now it leaks?

A Due to climatic considerations, inspections of shingled roofs and built-up roof systems are limited to a final inspection after the installation is complete. The final inspection is a limited inspection, which can only verify code compliance of the finish materials and cannot guarantee against any potential for roof leaks.

Boynton Beach