The most counterintuitive marketing tactic I've seen this year is also one of the cheapest: deliberately showing customers what they can't buy.
One travel operator ran a clean A/B test. The control group saw only available inventory, the rooms they could actually book. The test group saw the same availability, but alongside rooms clearly stamped "Sold Out."
It sounds backwards. Why advertise what people can't have? Because scarcity isn't a limitation, it's information. "Sold Out" tells the brain three things at once: other people wanted this, so it's probably good; the place is in demand, so it's a safe choice; and whatever's left won't last, so decide now. It quietly removes the hesitation that stalls a booking.
And it travels far beyond hotels. A restaurant menu flagging "Chef's Special, limited portions." A cinema showing "3 seats left at this price." Any moment where a flicker of demand validation makes an uncertain decision feel safe.
What I love about this isn't the £2 million. It's that the cost was effectively zero. An interface tweak. No technology project, no campaign budget, no new team. Just a sharper understanding of how people actually decide under uncertainty, turned into a design choice.
That's what good experimentation looks like. The smallest possible change, aimed at how people really behave, measured properly, and worth millions when you're right. The instinct to hide what's gone is costing more than you think.
