Switching the socket switch off should have an identical effect to unplugging. In both cases the circuit is being broken at the socket. At least, I think this is true though, not being an electrician, I may be wrong. Did your experiments compare unplugged with 'plugged into a switched ON socket', or did they compare unplugged with 'plugged into a switched OFF socket'? If the socket switch was on then the appliance would have effectively been in standby mode so it would be drawing current. If the socket switch was off then I am baffled that you found a difference.