Rewiring or replumbing a house

[Jordan Lagrassa]

the question is have any of you heard of or has had this happened to you. 

My father in law or boss has been in the construction business and roofing business for 40+ years now. He knows my goals in real estate investing and he warned me that there are certain situations you would be forced to rewire or replumb a house based on if it was up to code or not. Is this a logical thing ? I could understand if some shady wiring was done and having to redo that but rewire a house because the home didn't have power for a few months and now needs an inspection??? Thanks guys