It is rude to make unfounded complaints.
Jeri was going to dinner at her local restaurant.
Jeri wanted to get a free dessert at her local restaurant.
Jeri praised the food to the restaurant manager and then presented a coupon to her waiter that entitled her to a free dessert.
Even though she liker her food, Jeri complained about her meal to the restaurant manager so that he would offer her a free dessert.
Because Jeri praised the food, the restaurant manager gave the cook a raise.
Because Jeri complained about the food, the restaurant manager fired the cook.