The prior owner was a teenager, so you can do the math about why it was this bad. But I also have to say that Sony clearly made so many design flaws with the “fat” PS3. The shape of it was clearly meant for aesthetics, and not function. There are so many hidden places for dust to collect, and the airflow pattern isn’t optimal. These things are notorious for overheating.
Even after I cleaned it and replaced the thermal paste, it still runs pretty loud.
Unfortunately, a ton of games are still locked on the PS3 and not even available on PS+ Premium streaming, so having a PS3 is one of the only ways to enjoy those games (besides emulation).
As bad as it looks, that PS3 might well have sat in a clean house for years. There’s no way to clean them without taking them apart and many people don’t have the skill to do that.
There should be a user-removable filter that you can slide out and clean every now and then.
It must have still been a fairly dusty house or environment, at least in my experience, every ps3 I’ve opened up has only been moderately dusty at worst and my personal ps3 I got at launch was surprisingly clean inside even after nearly 15 years.