In my experience, plants love a certain amount of
sea salt, but if they get too much too often, it can kill them. Anyway, the right amount really perks them up and makes them greener. However, if you're growing watermelons, it can make the rind salty. I did have one watermelon with a very unusually sweet rind, however.
Blacktail Mountain had a salty rind on one fruit, and a second year Ledmon had a very sweet rind on one fruit (the largest, and most unique fruit in the patch). At least one other variety had a salty rind, but the other watermelons were normal with regard to rind flavor. Yes, I eat watermelon rinds. They make a great condiment if you peel the skin off the rinds with a carrot peeler and chop the rinds up into small bits with something like a food chopper or processor. Peeling the skin is just to make them easier to chop up (it's perfectly edible).
Sea minerals also seem to help plants against fungal infections and pests to some degree.
My sea minerals were kind of oily. I'm not sure why or if that's natural.
I did have an exceedingly sweet watermelon (I used sea minerals on it). I didn't notice much about tomatoes I had used sea minerals on, with regard to flavor (but I didn't use it on many varieties). I did use it on Pineapple, for sure, but it wasn't true to type (it was all yellow).