If you look at the photos closely you can tell the exterior isn't really all that perfect either. The paint on the hood seems to be pretty bad, as it is common for US cars that age in the hot south. And I wouldn't be surprised if the paint on top of the roof was also really bad. (Probably the reason why you don't see the full car exterior on the photos.)
It's always pretty hard to really tell how good a car's exterior looks on photos.
My black 1999 Explorer Sport for example has a matte spray painted hood (because the original paint had been peeling off from the sun and heat obviously). But other than that mine seriously almost looks brand new on photos, when I take the snapshots just after a car wash. But if you get close enough and look closely at it in real life you'll find little cracks in the paint all over the car.
My 1999's interior is a lot nicer than that, but to be honest that is mostly just because it has fabric seats and because I fixed the broken armrest of the center console when I got it.
The interior of the car advertised here is actually not all that horrible, as the first impression on the photos seems to show, to be honest.
The leather (or fake leather) of the driver seat is all torn of course, not uncommon for leather seats of that age.
But other than the terrible driver seat, the torn armrest of the center console (that can easily be fixed for cheap) and the discolored floor carpets the interior doesn't look all that badly worn and torn to be honest. Grey or beige carpets of cars with this age often tend to have discoloring and stains.
I don't want to know how it smells though, but I could imagine that a good vacuum, shampooing the seats and all carpets like they do in car wash and auto detailing places, plus 20 bucks for a new fake leather to cover the armrest and 20 bucks for a fancy set of shiny new floor mats from Walmart or Target and it would already look much better
...well yeah, the driver seat of course is a real SERIOUS aesthetic problem to be honest, and probably not very comfortable to sit in anymore either. Probably best to just throw some seat cover over the driver seat or to get a whole used seat from a junk yard...
Not that this specific car is worth the effort and the work, but if it were technically in a really great condition and just judging by the sparse photos here (you can't see the head lining etc. so I assume that'll be relatively okay) I'd guess the interior could most likely be fixed up to look MUCH nicer, for "relatively" cheap (depending on how far you want to go with it of course)!
I really don't think it's flood damage that discolored and stained carpets, probably just a lot of miles on the interior, a bunch of smokes, a spilled coke or two... maybe a half eaten fish burger living and crawling around under the seats...you know, the usual stuff you can find in old used cars.