You think that if you put AC across a capacitor no current flows?
You seem to be missing some basics here...
For the ghost voltage situation, putting a DMM with a 10M (or higher) input impedance across it is not going to load the voltage down a lot. You could easily measure 100VAC which might prompt you to start chasing down a fault that simply does not exist. The simple answer is to put an appropriate load across the measured points and then read off the voltage. Know your load and know your voltage means you know your current.
What is of
most interest here is not the actual current that flows but the voltage you read when the circuit is under this load. Because the capacitance that allow these voltages to exist is so low, the loading provided by a meter with a Lo-Z range often drops the voltage measurements down to zero - or close to. When this happens, your confidence that the circuit measured does not have dangerous power behind it rises dramatically.
Of course, if you still measure 100VAC (or whatever) on a Lo-Z range, then you
do have something to chase down.
I thought we were all engineers in here.
This is not helpful.
Most of us here have, what I call, "engineering minds". Some are qualified, some have experience, some have the drive and some, the ambition - but we all try and keep ourselves grounded in the way things work in the real world. You seem to be resting on the pedant pedestal a tad.
So, let me ask you this question...
Say you measure 100VAC in the normal high impedance mode of a DMM - and then measure zero when you switch to the Lo-Z mode? How much current is flowing? Ohm's law gives a clear answer.
Of course, theoretically we know there must be
some current flowing - but it's going to be one poofteenth of a gnat's wing - and as far as the
real world is concerned, that is
negligible (unless you're playing with atomic force microscopy or somesuch).
As a practical consideration, sometimes the theoretical needs to be properly understood - and put to one side.