The show tries out a beauty salon switch, swapping a super pricey cream for an economy product. Will customers spot the difference? A common trick of the restaurant trade is revealed. It's the 'we've only got one left' trick, where customers are encouraged to order the most expensive dish on the menu by convincing them there's only one left. And in the test supermarket, a shopper is equipped with a high-tech tracking device to reveal how shoppers are drawn to products on the shelves, and why.