Thanks guys. This question has nothing to do with theft or what is allowed, I just have always been curious as to whether anyone on the other end of the cable can tell if you have anything hooked up or not. Kind of the "big brother" thing you know. Like can Direct TV tell what you are watching, can the cable company monitor what you watch, general snooping stuff like that.
What reminded me of the question was the latest proposal in my "whacko" state to tax us on all the miles we drive. The tax is not what pissed me off, forcing us to pay for a GPS unit that will keep 24 hr surveillance on our exact location is what got my 60s paranoia going.