While the Spanish were baffled by Andean khipus (knot-based writing and accounting), the Incas were likewise baffled by writing.
Apparently some Incas saw the Spaniards learning things from merely staring at papers or "white cloths" and word began to spread that the Spanish had magic talking cloth.
A couple stories I read about today:
An Inca man came across a Spaniard reading a book and asked to read it. The Inca man held the book, flipped through the pages, and asked in confusion why it wasn't saying anything to him.
Another time, some Spanish hired a few Inca peasants to haul a wagon full of melons to a nearby town. They explained that they were not allowed to eat any of the melons, and that a paper receipt carried in the wagon would alert the recipient if any had gone missing. The Inca men decided to solve this problem by placing the receipt on the other side of a wall so that it would not see them eating any melons, and thus could not snitch on them.