Back to the topic though.
Between the water of where the hair-dryer was dropped in and the waste there would be a Voltage Gradient.
Regardless of the fact that there is no water flow down the waste, there is still a low impedance path to Earth.
There was a time here in New Zealand, under the 1976 Electrical Regulations, where a steel based emulsion-coated bath was required to be directly bonded to the main Earth Busbar in the Switch-board.
But, kick me if I'm wrong, I've never seen a bonded bath in the whole time that I've been an Electrician.
Hmm, must have been them trendy Aucklanders!. [Linked Image]