I've never knob & tube wiring in the living space. I've only seen it in attics and walls. I guess if it was fitted afterward, it would be where ever the electrician could put it. IIRC Romex style wiring came out right around WWII. My first house was built in 1946 and had the old style Romex with the cloth outer covering.
I used to do cable and satellite tv. It's been a very long time since I've been in the house of a serious chain smoker. There's not nearly as many of them as there used to be. Sometimes that "nicotine" that we scrub off so vigorously is actually the deteriorated shellac clearcoat too.
Rodney