I would lean toward the quality of the terminations (workmanship/talent)
You don't mention if the terminations are on the screw terminals, if it's #12 or #14 NM, or if the devices were 'backstabbed'
We come upon a few burnout receptacles, and IMHO, termination quality is an issue.
I am not aware of any device issues in the early 2000s.
As to your comment on the job being 'inspected', I am not aware of any inspector that has the time, or the authority to remove a device to check terminations. Perhaps there may be some, but none that I know.
