What does it mean to sell clean sugar cane and oranges at the bottom of the basket?

In Cantonese, "orange at the bottom of the basket" means "selling leftover goods"

The imbalance between men and women makes it difficult for single women to find partners, and they are ruthlessly labeled as "old aunts" and "selling clean crutches" by society.

Now it is generally used to describe that you can't find someone, or no one wants it, which is derogatory.