The Great Air Conditioner Swindle asks a simple question: are those cheap "portable air conditioners" all over social media actually air conditioners at all? During every British heatwave the adverts arrive with remarkable punctuality. Tiny desktop gadgets promise to cool an entire bedroom, lounge or office for the price of a takeaway. The videos look convincing. The claims sound scientific. The reality is often rather less impressive.

In this episode of Mark & Pete, we investigate the difference between genuine portable air conditioners, evaporative air coolers and ordinary fans, and explain why the laws of thermodynamics remain stubbornly unimpressed by clever marketing. We look at misleading online adverts, impossible cooling claims, energy use, humidity, why proper air conditioning always needs somewhere to dump the heat, and how physics quietly ruins many sales pitches.

Along the way we share plenty of facts, statistics and practical advice to help you avoid wasting money during the next hot spell. What actually keeps a room cool? Do ice packs really work? Why do ceiling fans make you feel cooler without lowering the room temperature? And why are so many nearly identical products sold under different brand names?

As always, there is a wider point. Proverbs reminds us that "the prudent gives thought to his steps." That applies just as much to shopping as it does to life. We live in an age where glossy videos appear before evidence, confidence often arrives before competence, and marketing occasionally seems to regard the laws of physics as little more than helpful suggestions. They are not.

Expect plenty of gentle banter, a few raised eyebrows, surprising science, consumer advice and a healthy dose of common sense. If you've ever been tempted by a miracle cooling gadget, or wondered whether that bargain air conditioner is too good to be true, this episode is for you.

Because sometimes the hottest thing in Britain isn't the weather. It's the advertising.