I wouldn't call that a ground loop. If there was something like that, it would cause the ground to be noisy.Could it cause a ground loop hum?
04-23-10: Atmasphere
Why would it be any different than ground current flow from a CATV system? In both cases current is flowing through the equipment ground. We know current will take any provided path back to the source. If the ground current flow is present what would prevent it also from flowing through the ics signal ground to other three wire cord and plug safety grounded equipment to get back to the source?

