Spices: The most commonly faked spices are saffron, black pepper and paprika. They're EXPENSIVE spices, and easy to fake. In some cases less expensive stems. The way to know their not fake? Buy whole spices and grate/grind them yourself.
Coffee: Ground coffee is frequently cut with other ingredients to make it stretch. Buying whole beans and grinding them yourself resolves the issue.
Olive Oil: The USP determined that Olive Oil was one of the most faked foods in the world. The secret to knowing your olive oil is safe? It should smell alive and vibrant, like grass, flowers, or pungent olives. It is also recommended to purchase oil manufactured/grown in the United States. It will be fresher and authentic!
Seafood: The study found that the cheaper Escolar (which incidentally is banned in Japan and Italy) is passed of as White Tuna or Butterfish. Further, fake scallops are commonly made by cutting scallop sized discs out of shark meat. The key? Look for familiar fish that has been harvested in the US, particularly Halibut and Pacific Salmon. With Scallops, look for irregular shapes and sizes.
Hamburger/Ground Meat - With the recent horse meat scare throughout Europe, eating a hamburger can be ground beef roulette. If you're concerned, ask your meat counter if the hamburger was ground in store.
For more information from Chef Tom, please visit his website: http://www.cookwithtom.com.