"Made in China" ... but made of what?

There's been a recent explosion in news about fake products manufactured in China - some exported, and many sold domestically. Not flimsy golf clubs or shoddy Olympic 2008 T-Shirts, but potentially fatal fakes:

• Fake plasma used in hospitals that contained no protein
• Fake Toothpaste: Colgate-Palmolive said counterfeit "Colgate" toothpaste that may contain a toxic chemical had been found in discount stores in four U.S. states.
• Petfood that contained Chinese wheat gluten contaminated with melamine is responsible for more than 100 pet deaths amongst nearly 500 cases of kidney failure