Good question! It's very possible that they weren't. I have long suspected that when Bitmain first manufactures their machines they run them in their own mine for a certain period of time, and then pass them off to their customers. Maybe the bigger miners get the least worked machines because they spend the most money, and the smaller purchasers get given the older machines with very little life span left. And if you claim warranty then maybe the boards they send you have even less life span, which seems to be the case with my replacements. It's a pretty good racket when you think about it. It's the perfect way to get rid of their old stock, because the machines are useless past a certain point.

I have heard that there is a lot of corruption in China, and I would not put something like this past Bitmain. They are either doing this, or just selling a very low quality product. Either way, they cannot be trusted.