My take was that was always essence of the "dogs smell Terminators" plot element. Skynet could make Terminators that looked and acted human, but didn't put the

My take was that was always essence of the "dogs smell Terminators" plot element. Skynet could make Terminators that looked and acted human, but didn't put the effort into making them smell human. Unlike us, a dog's sensory world is more like 50% smell and 20% vision. Ergo, Terminators seem "obviously wrong" under even a cursory examination to them.