No quality control
I had no problems with a small previous order, but in the second one, on a double-sided board, they put top side traces on the top side, which is fine, but on the bottom side, they put not just the bottom side traces, but also the top side traces, effectively shorting them. I had never come across a manufacturer that would make such a silly mistake! I contacted them about this problem, and at first they did not take the complaint seriously. After some insistance, they recognized their error and replaced the parts.