[arcticfox]

This doesn't make any sense at all as a major problem. Used vs. new is basically irrelevant as long as no one is lying about the hashrate. As long as the sale is immediate there's basically no problem at all there.

The actual problem, especially in the past, was that you could pay for the hardware but not actually obtain it for months, by which point it was no longer profitable. Presumably, the manufacturers were using the hardware themselves during that period.

[SippinLean]

It was certainly a major problem, if you bought a new car but the dealer gave you one with 50k miles on it would you shrug it off if the gas mileage was still the same? At a basic level it's fraud.

There are practical concerns as well, these machines are usually pretty poor quality and the immense heat + poor cooling typically means the chips will burn out one-by-one over time. The PSUs are especially poor and will burn out and need replacing as well. Getting a used ASIC means these will be problems sooner.