 A dull sort of sound, like a hollow sound. If you get that kind of hollow sound, it oftentimes means that the watermelon might be a little bit too ripe. Belly Sugar Farms co-owner Myron Franklin says the first thing to look for is a non-shiny, dull exterior. This news sponsored by Swallows Insurance. Swallows can protect your family, searching a number of companies to find you the best insurance option.