More worrying is when people install brass / metal switch plates in 1960s/70s wired houses and don't bother hooking up an earth.
I had one some time ago in which the light fitting had been replaced with a combo fan/light, and the switches in the living room had been changed to brass types. The report was of "slight tingles" when touching the plates sometimes.
All the earth terminals on the fan and switches had been carefully interconnected
with new T&E and 3c+E cable, but the feed was then spliced to the original non-earthed lighting circuit, the earth just left disconnected.
Given the circumstances, it would actually have been better to have left
all the earth wires diconnected to avoid the combined capacitance and to avoid the possibility of "exporting" an earth fault from one point to another.