I remember those old cellphones with weak IR filters. It was a scandal because light clothing turns out to be more transparent to IR than to visible light so they were acting as a sort of clothing "X-Ray" in bright light. Creepers on the Internet tried to start a whole new genre of porn but were shut down in a hurry by cellphone manufacturers adding robust IR filters on the next generation of smartphones.

Shame that perverts had to ruin that for us, it was kinda neat to point a TV remote as the camera and see the bulb light up.