I have taken three types of pictures.
Type 1 - where I have been called to repair/replace an existing shoddy install, and I take "before and after" pics to show the HO and any inspectors.
Type 2 - While conducting inspections with the FD. Since our fire inspections cover the whole premises, and a lot more than just wiring & methods, the pics can either serve as "evidence" (not really since IL hasn't recognized dig as evidenciary yet IIRC) for follow up inspections, and as reminders for the "certified" inspectors to check the Code when they get back to the station.
Type 3 - The "No s***, there I was, minding my own business when a ten foot tall code violation jumped me, and forced me to take a picture of it..."
Obviously, with #1, I'm there to fix the problem, so having consent usually isn't a deal. #2 is in the context of a legal inspection by sworn officials in the performance of their duties (Howdy, AHJ's!), so it's usually never mentioned. #3 is covered by the same general principles that others have mentioned: Don't say
EC "x" installed this )(!(&*^$( work at John Doe's house, at 1234 Main Street in Anytown, USA... come see!
As long as there are no damages (including financial from a "bad rap" resulting in drop in business for an EC, or 'mental and emotional suffering' due to libel/slander for a HO) litigation is more difficult to successfully pursue.
They're a great learning tool - even used afew for "in-service" for the inspectors at the FD. Don't name names or addresses, but keep the pics comin'!