My advice for anyone who wants to buy equipment to start mining is that if you can afford to get the new one, go for it and play the long game instead of trying to save some little money on fairly used that are more prone to developing a fault.
And this is a point where you should probably share some real-world experiences to make a point.
New mining equipment that has just been released can be crap too, Bitmain has made a series of flops where it has released garbage miners that would break far faster than you would have expected even from a used miner, and it has done so even on already proven versions, releasing a new batch that was nothing like the previous. With used miners and trusted sellers you don't just have the price advantage but you know those were proven miners that ran for years and had no issue, so it's more like a lottery but with no real fixed odds.
Is there any research or data related to this? I'm always curious to see whether or not ASIC is prone to failure when people run it 24/7 just like GPUs. Some news report that some model has a high failure rate, such as this one[1], but I can't find any reliable info on this.
You can find enough stories confirming this on this board, the s17 was really bad, even for Bitmain.