Bogus ad!!! Two totally different cars! (Or one before repaint and one after.) https://inlandempire.craigslist.org/cto/d/lake-elsinore-1976-oldsmobile-98/7165457102.html
It is weird. The right side has different tires, too. Notice that the molding that runs along the car about half-way up the door is missing from the right rear fender. It almost looks like the passenger door and right rear fender were replaced, perhaps due to an accident. That might account for the missing trim and also for the paint on those portions being a slightly different shade. Perhaps when those sections were repainted, no attempt was made to blend the paint with the rest of the car, which could have faded if the repairs were made years after the car was new. But doesn't paint usually fade to a lighter color? So the replaced pieces should be a darker shade than the rest of the car? I don't know.
Its the light from the open garage door that is washing the color out of that side... The other side is unnatural light from the lamps overhead and is in the shadow of the light from the door... Look at the hood as it has less natural lighting from the door directly hitting it. Simple photography lighting skills, if he'd have closed the door it would be even all the way across with the lamp lighting overhead. ETA: you notice the lighting reflecting from the open door on the other angle if you look at the truck in the background, also the vinyl absorbs the light unlike the paint which reflects the light which is causing it to appear lighter.
I agree with Leadslead. It's the lighting. I've seen (and owned) many cars where the trim on one side is gone or damaged and they didn't make any attempt to replace it. Judging by where it is and the shifter being in N, I presume it's been stored for ages and just been pushed around to roll without starting. Also the door hinges are worn as both doors appear to be sagging. It seems a bit pricey for a car that likely will need some effort to get running again (battery, fluids, etc). I think he'd have more luck getting that price if he could show it was a runner and driver.
I'm not sold. There is definitely a difference in shade. This photo shows it pretty clearly. The open garage door doesn't account for the contrast between the trunk lid and the rear quarter. It looks like the entire right side was replaced, and the missing trim on the rear quarter would support this. Perhaps the original was damaged beyond repair, and they haven't found a replacement.
This photo is more interesting. The top of the right front fender is a darker shade than the side. This would support the idea that the side is faded and the top is not. This car would have had to have been exposed to sunlight from that one direction for a LONG time for it to have faded that much on the exposed side.
Fading could be sun damage but also common for repair level single stage paint resprays to dull out on their own. After all, this 98 spent a lot of it's life as just an old car before it got so old it became interesting.
