A shopkeeper in the Fairygrounds is entirely incapable of being nice to his customers.
This errand is available after defeating the Royal Jelly in the Fairyground.
The shopkeeper east of the Cawtermaster is in dire need of kindness. There's none available in the town of fairies - odd - so you'll have to wait until you progress further in the story and return it whenever possible.
The kindness becomes available in Ding Dong Dell after defeating the Candelabracadabra.