How Can You Tell If a Watermelon Is Bad?
Check if your watermelon is still fresh for eating by inspecting, slicing and smelling the watermelon. Watermelons have a shelf life of seven to 10 days, or two to three weeks in the refrigerator. After the melon has been cut, however, it beings to go bad quickly.
Inspect the watermelon
Carefully examine the outside for signs of mold and dark-colored spots, which could be an indication the inside is rotten.
Slice the watermelon
Cut into the watermelon. The inside should be deep pink or red in color. Otherwise, do not eat it.
Smell the watermelon
Bring the watermelon close to your nose and sniff it. If it has a tangy or sour smell, throw it out.