Overcharging Blue Field Wire Grounded

Sorry my friend, not true. A switched wire such as that WILL show continuity to ground, because of the other branched loads on that circuit, and depending on car and year, that might be--VR, ignition system, electric choke, idle solenoid, and a couple of smog doo dads. Again this varies.
Yeah, I agree, I didn't think it through... Since I never try continuity tests on a powered circuit I failed to consider the loads..