Power cable polarity

I have two questions.
1) There is a theory that power cords should be plugged into a wall socked in a certain position/polarity which can be verified with a test screwdriver (with electric bulb - I don't know its correct name). According to this theory, in order to check the correctness of the polarity, one should insert the screwdriver's blade into the right slot of the male IEC connector (or whatever it is called) which connects the power cord to the chassis IEC inlet. If screwdriver bulb lights up, it means that polarity is correct. If you insert the screwdriver blade into the left slot of the connector and the bulb lights up, then the polarity is wrong.
2) The opponents of this theory argue that we should check the correctness by ear and should be able to determine whether it is right or wrong. I recently connected a I have two questions.

I live in Russia and use Schuko plugs and European wall sockets.

I will appreciate all comments and opinions.
In the USA: electrical code requires the hot(120-130V/60hz/usually black) wire from the home's breaker to connect to the brass colored screw on an outlet(the right slot from the front), and the neutral wire(no voltage/usually white), to the nickle colored screw(left slot from the front). I believe in Russia the standard voltage is 220/50hz. Here in the USA 240-260V circuits(single phase) have two hot terminals(120-130V each) and no neutral(there is a ground terminal though). That's probably how your home AC is provided as well. With our 120V system: If the phase is reversed between two components, it usually results it audible hum(60hz). If your phase is reversed with 220V, between two components in your system, YES: it should be audible. If you run into that: reverse the hot wires of one powercord plug, and try the listening test again.