People have also been known to spike wine with diethylene glycol and/or ethylene glycol to enhance the sweet taste (both glycols are sweet, but highly toxic).
Here a few years back, the Chinese adulterated food with melamine (used in plastics, and very cheap) because it appeared as a higher protein content when the food was tested.
One time recently, my company ordered 300kg of a chemical from a Chinese supplier. It came in as 3x 100kg drums, all marked with the same lot number. The appearance of the stuff should be a white crystalline powder, much like sugar.
One drum was a nice white crystalline powder. The second was very pale pink, and the third was a very light tan. We immediately had analyses run on all three drums, and fortunately for us, all were the right substance, and the material was satisfactory for our need.
Moral of the story, don't trust your suppliers blindly, or as Ronald Reagan said, "Trust, but verify!"