I wouldn't say that they're bad for you, but too much of anything can cause tummy or digestion issues. If you're able to get a seedless watermelon to use for these recipes, that would make it an easier prepping process. However, if not just do your best to get the seeds out and toss them in your garden. Who knows, maybe you'll be able to grow your very own watermelon next year and not have to buy any at the store!