I love watermelon. I have pretty bad luck in picking a good watermelon. I've tried thumping them and listening for a hollow sound. I've tried picking one that has a large yellow patch thinking it means it was on the vine a long time. I've tried picking the darkest green one I could find. Still, it's hit or miss. Fortunately, I'm on my second watermelon of the season and both have been very, very sweet and tasty. But I know soon my luck is going to run out. I can pick a cantelope pretty well. You can smell the ripeness with those. Not so with the watermelon. So, do tell. What is your luck in picking good watermelons and what is your technique? Maybe grocery stores should have trained watermelon ripeness sniffing dogs for us to use.