I have been wondering about that my self, and planing to test it out.
here is my plan:
use my existing PF meter and check the power factor of an inductive load like a motor.
then turn off the power for the entire house. and power the motor only.
use a stop watch and check how long it takes for the electric meter to complete one turn.
then correct the power factor and check the electric meter again.
from what I read about PF, it can only be adjusted on inductive loads.