Electricity meter Older "dumb" meters have caused trouble because they led to bills being estimated
Only because they couldn't be bothered to send people round to verify / send blank card for householder to complete.
Another trick involved placing a strong magnet on the smart meter to stop it collecting usage data while still providing power.
Nice. Noted for if (when) I'm forced to have one and the signal is somehow able to escape the ersatz
Faraday cage that is the understairs cupboard...