I used to send a complaint for faulty products to companies in my late teens/early 20's as I was low on money. Like once I got some energy drink in a bottle made for Pepsi. Same volume, no difference, but a mistake, so got 5€ for it so "won" like 3€ for that. I'd pick out products like that if I saw them in a shop for that very purpose.
Once I genuinely was annoyed though, as a soft drink company that filled the vending machine at our school had filled it wrong and I got what was essentially Fanta he I wanted an energy drink and it was fucking hard waking up that morning.