There are many reasons why cats like to dig into shoe racks:

1. As a three-dimensional structure full of various "smells", the shoe rack is an attractive space for cats to explore. They like to get into various cracks and small spaces to satisfy their curiosity and desire to explore.

2. Shoe racks are usually located in areas where human activity occurs, such as the living room or bedroom. These areas are also a part of cats’ lives, so they will tend to seek out places to rest and play in these areas.