I was on a Spirit return flight from Chicago a few years back and the seats were actual plastic. Hard plastic, no cushion, and had that bumpy elementary school red ball texture on them that just irritates your ass instantly. I stood most of the flight. Air travel is getting worse and worse for the common schmuck but it still beats walking.
We flew Delta for the first time in October, (because United canceled).
Sure learned why they're ranked like they are.