Consumers have been warned to avoid wasting their time and money on dud kitchen gadgets.A list by Which? of the money-wasting products you dont need includes peanut butter makers, tumble dryer balls and gas energy savers for kitchen hobs, the Daily Telegraph reported.While tumble dryer balls, which are sold by John Lewis and Lakeland, are marketed as ingenious, eco-friendly laundry balls, designed to reduce drying time, Which? claimed that they actually increase the average drying time and fail to achieve improvements in creasing or softness.Meanwhile, Which? also suggested that smoothie makers are more hassle than they are worth.Our lab tests show that even the best smoothie makers can be really tricky to clean thanks to their tap dispensers, and theyre often slow to pour, said the magazine.Instead, it advised using a standard food blender.Earlier this week, a report by the Associated Press suggested that people can make their homes more functional and better equipped for cooking by installing a second kitchen sink.