«Daydreaming in the Shoe Shop» by Martin Lundqvist

The protagonist enters a shop with a sign saying ‘New shoes traded in return for your old shoes.’
Once inside the shop, he meets the proprietor who tells him the importance of walking in other people's shoes.
Once the protagonist is about to pay for the shoes, the proprietor is gone and the shop attendant expels the protagonist for trying to pay his new shoes with his old dirty shoes.