More to the point, "Smart Meters" can give a detailed record of power use, which can be analyzed to show power usage room by room. With access to a "smart power meter" and a database to for comparison, an enterprising soul can tell when you are in the living room watching TV and how many slices of toast you had for breakfast that morning.

It is inevitable that "smart" power meters will be used for incredibly detailed, ubiquitous surveillance.