Testing ripeness
I have another option for checking ripeness. An older Hispanic man saw me struggling to pick out a watermelon at the store one day. His suggestion was to first look at the end opposite the stem end to see if the little "button" is black. That's a good thing. Then, he said to rub my fingers across the rind. If it feels sticky, it's ready. I haven't picked a bad one since he offered his wonderful advice!