Anything worth counterfeiting likely is. A mass-market Dan Brown novel? A book is a book; as long as it's in English, you don't expect much from it, and it won't explode if improperly printed. A first-edition Lord of the Rings? Yeah, no. At that point it's less a book and more a collectible.

Software is also pirated on Amazon/eBay-- everything from resold OEM licenses (sans disc) to hacked binaries (sans DRM).