Make sure you never connect it to the internet either.

TVs can record snapshots of what's being displayed on screen and send it for analytics. They're supposedly only recording a scattering of pixels throughout a screen and trying to match it to those same pixel values at the same positions generated by scenes in known media properties, which would in theory mean they can't really recreate what is actually on screen or identify any media personal to you that's not on their media database. (Honestly even that is creepy as fuck.)

But since the code is proprietary, who's to say they're not just taking full blown screenshots of literally what's on screen every now and then? If they sent a full screenshot and compressed it with LZMA or something on the highest compression power, every hour or so and slooowly sent it a few bits at a time over the course of that hour, you'd most likely never notice since it would likely be encrypted with SSL and not be so much data that would be easily discernible from other random network activity from someone who was monitoring their home network traffic. They could totally say it's simple HTTP requests for software updates or grabbing the latest Netflix listings or whatever. (And even then very few people actually monitor what their devices are sending. Even companies that eventually had scandals where they sending unauthorized analytics frequently and in plaintext, as in you only had to hook it up to Wireshark a single time to realize what they're doing, still manage to get away with it for years before someone noticed.) Or, the TV could be built with a trigger where it normally doesn't record your screen, but if you were a person of interest, they could start monitoring you whenever they want by sending a signal to your TV.

And I'm sure if you at any point connect your smart TV to the internet, it's definitely been caching all those past analytics to send in one burst. So don't do it.