From wiki:
The system can measure both
reactive power and
real power. Hence two appliances with the same total power draw can be distinguished by differences in their
complex impedance. As shown in figure 8 from the patent, for example, a refrigerator electric motor and a pure resistive heater can be distinguished in part because the electric motor has significant changes in reactive power when it turns on and off, whereas the heater has almost none. NILM systems can also identify appliances with a series of individual changes in power draw. These appliances are modeled as
finite state machines. A dishwasher, for example, has heaters and motors that turn on and off during a typical dish washing cycle. These will be identified as clusters, and power draw for the entire cluster will be recorded. Hence “dishwasher” power draw can be identified as opposed to “Resistor heating unit” and “Electric motor”.
So what I get from that is each device has its own fingerprint kinda. I imagine you could make your light look like something else using some device to transform the properties of the electricity being used to resemble a different appliances usage. Giving it a different fingerprint.