[Roadtrip]

A bad/dirty/loose GROUND Wire will not cause current loss. It will likely result in erratic operation of the item it's associated with, because the circuit is not being completed continually.

A hot wire that has a break in the insulation and is touching a ground (car body, sheet metal, etc.) will allow a freeflow of current and loss of battery power. In addition it can be a fire hazard because of the possible heat generated. In essence, with the high amount of current passing through the wire, it starts to act like a heating element.