It takes a long time to wear out a Birkenstock, a favorite sandal of Boomers (with or without socks). Here's a comparison of a new pair to an old pair worn daily
Birkenstocks Care - How to Make Your Birkenstocks Smell Good?
How To Make Birkenstocks Less Smelly, Because Sometimes The Odor Is Too Real
3 Ways to Clean a Birkenstock Footbed - wikiHow
Amazon.com: Birkenstock Women's Florida Soft Footbed Sandal, Habana Waxy Leather, 38 M EU/ 7-7.5 M US : Clothing, Shoes & Jewelry