Not everything at Costco is a great deal. The bananas have a ripening problem. The mayo container outlasts the product's quality window. The spices lose their potency before most households work through the warehouse-sized container. These realities exist, and the best Costco members know them. But for every category where the bulk format doesn't work, there are dozens of categories where Costco's institutional buying power, Kirkland Signature quality commitment, and 14 perce