Costco shoppers have given thousands of 5-star reviews to certain items, deeming them indispensable. However, not all products at Costco are considered must-buys, with some items being regretted by shoppers and others being deemed unnecessary. Various experts and shoppers have weighed in on the best and worst items to purchase at Costco, with some products receiving high praise from chefs, nutritionists, and superfans.