Understanding marketing tactics is a good way to learn how to be more skeptical about them. Knowledge can help you take off that wool you didn't know had been pulled over your eyes, and see the truth behind the lies, and hopefully be able to make a better decision about where and how to spend your hard earned cash.
Breakfast on 1 recently hosted a physiotherapist advertising the Shakti Mat - a yoga mat covered in plastic circles, with each circle consisting of 20 or more sharp spikes. The mat is supposed to work like a bed of nails, activating acupressure points. I've seen the mat sold at shows such as the Go Green Expo, and have stood on one - the points are really sharp, and without socks it was especially painful.