The Probably Stolen display case guide begins before the shutter opens once the tutorial unlocks the case: show the category you want to trade, then keep enough matching goods in stock for the buyers it draws. A display item is a signal to visitors, not merely decoration.
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Probably Stolen display case guide: daily setup
Check the category tags on the goods you want to sell.
Put representative stock in the display before opening the shop.
Keep additional matching stock accessible for customers who arrive because of that category.
Open the shutter and observe which buyer or seller types turn up.
Adjust tomorrow's display based on the stock you can actually supply.
Set the display before opening
The day's customer mix is influenced at opening, so moving goods after the shutter rises does not necessarily change customers already queued. Shop signs can also attract seller types. If you need more storage to keep matching stock ready, use the inventory guide before buying a second production machine.
When traffic does not match the display
Check the item's tags rather than its appearance. An empty water vessel can count as a household good while a filled one counts as water. A customer can also ask for a category that was present when the day started even if you sold the last item later. The demo patch also adjusted budgets for some buyers drawn by the display, so compare the actual offer with what is on your counter.