They peer through curtains; they make spyholes in cubicle walls, and with digital cameras they hide cameras in ceilings and books and showers and shoes.
Voyeuristic porn is a category. Upskirt is word popular enough to have an understood meaning.
I'm a bloke. I'm not worried by those creepers.
But I am uneasy about some users of Google Glass. I'd be really uncomfortable if I was standing at a urinal and someone was next to me still wearing Google Glass.