My mom's old trick for finding vintage denim still works today
She showed me how to look for thick stitching and certain brand tags from back in the day... I tried it yesterday and scored some awesome jeans. Things have changed, but some tricks never fade.
Last Tuesday at Goodwill, I saw jeans with that thick stitching. It reminded me of your mom's trick. @claire279's story about the flea market find fits right in. This is how we find quality in a throwaway world. My grandma could spot a well-made coat by the lining. Those skills are like secret codes.