I have a Sony Bravia Smart TV. The only thing I use on it is the screen, the power button, and the volume control.
Everything else is handled by the Internet connected Amazon Fire TV stick I plug into it. It is effectively a dumb TV and will not get infected by malware.
I have an LG with WebOS and try to use my TV the same as you. I don't have it connected to wifi so it's unlikely that it will get infected with malware anytime soon, but it did crash yesterday when I turned it off at the end of the night. I had to pull out the power plug to turn it off.
That's one thing that never happened to me with a (truly) dumb TV and I've only owned this one for a month. I sure hope the CPU hardware running this OS doesn't degrade as quickly as normal consumer PC hardware and I can expect it to run as quick and reliably as it does now in ten years from now (like the TV it replaced did).
I would agree odds are low of something that insidious... but it's hard to say "it'd be impossible for my TV to get hacked" when even light bulbs are getting attacked.
