Fast-food companies spend years inventing and testing new menu items. 
But even with careful planning, things can still go horribly wrong. 
Look no further than McDonald's Mighty Wings. The item did well in test markets, but when they launched, customers found them too spicy and expensive. 
Mighty Wings are hardly McDonald's first menu flop, nor are they the only chain to have suffered from them. We also found failed items from Wendy's, Pizza Hut, and more.
Kim Bhasin contributed to this story.