In "Animal Crossing New Leaf," my friend's "perfect fruit" turned out to be rotten. How do perfect fruit turn rotten?
Fruits in New Leaf do not rot. On a perfect fruit tree, one of the last fruits it produces before turning into a regular tree will be rotten. Don't try to sell the rotten fruit, everything else you sell at the same time will be rendered worthless and you will have to pay a disposal fee.
Turnips do rot every Monday, but they are the only items in New Leaf that rot with time.