In my entire life, I have never once plugged anything into the USB port of a tv, not have I ever had a USB port on a TV cause a problem that needed me to inspect it.
What exactly do you do to USB ports?
2. Are we next going to discuss whether one of us has used the HDMI port or not? :)
And to answer you question: I used to insert a pendrive quite often to inspect Linux ISOs before I had FireTV on which I was able to install a general Linux ISO inspector app.
If I had to go poking around back there, the toilet paper would have at least piqued my interest.
Without the toilet paper, I would have simply assumed whatever was plugged in there was officially sanctioned.
I mean, Nixon bugged himself, right?