I'll never forget when I sold my last house, the HI spotted a twin 15 amp (BR1515) in my shed's sub panel for two separate 15 amp circuits. He stated in his report that I either had to replace the branch circuit wiring with #10 or put both circuits on one pole of the breaker because 15 + 15 = 30 amps.
Where I will defend an HI for not following code is when they do recommend upgrading "grandfathered" things that involve safety. Pointing out missing GFCIs in bathrooms is a valid concern as long as the report has language like "although not required at the time of construction of this building, current safety standards require GFCI ..." Sometimes they even get those rules wrong though.
