Re: Bad earth.
Grounding to a water pipe -- used to be a common practice. My first house, built in 1939, bought by me in 1977, had been replumbed in the basement from the original steel pipe to copper, though only where it was easy to reach (in the walls the original pipe was left.) The electrical system had been grounded to a cold water pipe, and the original clamp, sized for the larger diameter steel pipe, was left hanging loosely on the smaller diameter copper.
It got better. The 60 amp mains panel, with no master shutoff, was right beside a metal shower enclosure that had been added in the basement, so if you worked in that panel (live of course) you were right beside a good ground. All the 3-pin outlets added in that basement were ungrounded. You could measure an induced voltage of about 30V between ground and neutral in the furthest outlet. One outlet had the hot and neutral reversed.