Years ago, I noticed some dimmers left a small amount of power running to the blubs.
But, that was when the brightness was turned all the way down.
When I pushed the OFF/ON button, the dim lighting was gone.
Last year, (or maybe 2011) I installed some X10 switches and found they leaked
a pretty good amount of AC to the lamps. IIRC, it had to do with that model X10
had load-sensing, to turn on the lamp using it's off-on switch!
If you are using low voltage LED lamps and are shutting off their DC power-supply,
using a standard AC off-on switch, running dim when off is not possible.
Since standard 120vac 15A wall switches don't leak power (unless underwater).
Maybe an expensive switch has a capacitor to inhibit arcs..?.
If you do see dimly lit low-voltage LED running on 'free' power from outer space,
you might be living too close to a large radio transmitter..
