Before anyone asks, you can buy a TV that’s dumb. Look on Sony or Samsung or business kiosk TVs. I bought some Sony kiosk TVs for conference rooms when building out an office ones. They can be left on forever have the same great quality and cost a little bit more. But they’re dumb in the end and they turn on fast.
Iirc, in the earlier days of LCD tvs, the ones meant for digital signage sometimes had different color calibration, and also sometimes had weaker processors than their consumer bretheren because they weren't really meant to display high-framerate motion content, and were mainly used for static images. A friend's dad picked up a few for cheap when their employer was updating some of the ones they used for digital signage, and they struggled with some types of 1080P content, especially when the images were messy and rapidly changing (think close up tracking shot of a soccer game.)
Not sure how relevant that is today, but likely still something to watch out for especially if you're looking for a cheaper dumb TV. Also, if you're getting a used digital signage TV, if you can try to run through some basic color and motion video tests on it before you buy it; mostly to check for burn-in and backlight quality.
Also, are there decent OLED dumb TV options available yet? I rarely watch anything on my TV, so when I do it's generally something more 'special' and I rather like the gamut that OLEDs offer for those occasions.
Bet money on it being the garbage smooth frame stuff that pushed the TVs to fake 60 or 120fps by guessing frames. Even my newest 75" TV has this junk and makes the picture stutter enough that it drove me bonkers trying to turn it off - Google TV is awful for this but the TV also lets you fully turn it off on some ports.
