The problem is today's Windows PCs are a varied lot. One might be faster at video editing, another gets the nod for gaming but used is all over the map. What if it was not taken care of?
If I see filth on the inside it's a bad sign. But the seller is usually too high priced in my view when I can get a new model for so much. I use the 50% per year price scale.
The 1st year is 50% off. And the second another 50% If the market for the new ones goes down, then I adjust downward to match. I will not listen to "I paid this much for it!"
There's a reason they are selling.
How can I check the desktop hardware, how it is spoiled?
If I buy a second or third hand car, I will bring a car mechanic specialist, he will drive the car & he can find how far the engine is spoiled, same way how can I check computer a faster one from the many used one