It's definitely something that I worry about a lot. I don't have dogs anymore but used to and I wouldn't want anything nasty to happen to them due to adulterated or contaminated food. The last major recall was due to unscrupulous manufacturers in China adding melamine (a form of plastic) to there pet food in order to make the protein content appear higher when tested in the lab. The melamine scandal got worse when other manufacturer's added it to milk formula for babies so that's when everything went really, really out of hand.
I do not think I could ever trust products made in China especially the cheaper stuff! Who knows what else they've got in there!