Guarantee by guarantee. But, for example, the laptop may have been flooded earlier. Something will get damaged in the end and you will flood it, and there is no guarantee for it.
Without watching it live, there is some risk of buying. Is it worth it? It depends on the price and whether you can deal with them in case of any problems.
I bought some laptops over the net, some blind. But they are mostly either Toughbooks or ThinkPads. So, in general, equipment is damn resistant, not game-like inventions.
One was slightly flooded, it turned out after about 5 months. The power diode gently began to change its brightness. But a quick reaction and it was possible to save him before the corrosion would make a big mess.
You never quite know what happened to the equipment before.
And stuffing faulty equipment in pawnshops? Standard

In general, poor knowledge of the recipient, and the thought that the owner will probably pay it back and take it back.