[fest]

Having ordered lot's of cheap prototype/evaluation boards through dx.com/ebay/aliexpress.com, I can say for sure, that quality does differ.

Seed and co have higher standards for soldering/reflow quality, wheras random factory churns out boards, probably even not doing any sort of testing apart of "hmm, looks connected".

That being said, most of the stuff still works fine despite shobby soldering and cheapest parts they could get at the market that week.