When it comes to picking sweet and juicy watermelons, look for sugar spots. These dots are pollination points from where sugar seeps out of the fruit.
Instead of tossing the blemished watermelon, stick to one with these sugar spots. They indicate that there is plenty of sugar inside, and thus the melon will have a sweeter flavor.
Sweeter watermelons will not only have sugar spots and a darker color, but they may also have a large yellow patch and webbing.
A shiny watermelon may be a sign it isn't ripe. Ripening stops as soon as it is off the vine, and if you pick an unripe melon, you'll have it till it spoils.