Wouldn't a double pole switch get rid of this?
Break the neutral and no current flow.
But that involves re-wiring probably.
You are on the right lines, it is the fact that the switch does not have the neutral taken to it with the line. The problem is complex, it's called transmission lines and any cable is considered as a series of capacitances and inductors and if the line and neutral are the correct distance apart then they cancel each other out. However at 50 Hz we really do not worry, once you get into the MHz range then very important.
Radio people measure the voltage standing wave ratio and go to great lengths to ensure the circuit is balanced, but with lights it really does not matter if the light stays on dim, adding an inductance or capacitance to correct may be the theoretical cure, but in real terms we simple leak away the excess bypassing the lamp, be it CFL or LED. Only real cure would be DC.
The war of the currents was interesting, USA had some DC supplies right into end of 20th Century and the pros and cons DC v AC are now leaning more to DC with modern technology. But the ability to transform to high voltage for long runs then back to low voltage for local use means even if there are some losses the net result is AC wins.
If
you can light fluorescent tubes under power lines then clearly some power is being radiated, however when compared with power lost with conversion equipment to use DC it is still best way to send power around the country and your house.
It does not have to be bulbs lighting dimly, silly LED and Neon lights on routers, TV's printers, etc can illuminate a bedroom, I spent ages sticking bits of black tape over them all the other night.