I didn't work with this idiot, but I had him working for me through a contractor.
My wife and I restored a 100 year old Victorian house on Galveston Island several years ago and gave the A/C work to a friend's son. The son let one of his workers do the job. The joker used 100 year old pine bead board paneling I had painstakingly removed from the interior walls to build the subfloor for the A/C unit in the attic! When he cut openings for the vents in the wood floor, he cut the holes too big for the vents, forcing me to patch every single opening. He connected the two electric heater elements to a single 30amp wire, leaving a second wire hot and dangling against the furnace enclosure. The guy was so stupid, I told my wife he's lucky breathing is an involuntary act - if he had to think about it, he'd suffocate.