The "sea salt" myth is one of the biggest hoaxes ever pulled on the culinary profession. All salt is "sea salt" (except sweat), some was just deposited 100 million years ago, and some was formed through evaporation yesterday. All is derived from sea water or saline lake water.
All natural salt deposits regardless of age have pretty much the same properties. The impurities that some say distinguishes one fancy salt from the other are the same. Sea water has a amazing uniform distribution of elements and minerals other than NaCl where ever it is found, and over time(with a few exceptions like landlocked salt lakes).
What is perceived as differences in salt taste is generally a difference in texture or color. There is no doubt that salt grain size is important when considering how salt is used as a rub component.
Color of salt is from impurities such as manganese, magnesium, potassium, and iron. Anybody know what manganese tastes like? - I don't. The natural salt deposits are mined and then the salt is processed by grinding, adding iodine and some other chemicals that help it pour and be healthy. The Salt Institute informs me that all salt sold here for human consumption must be 99.9 percent NaCl.
I would be impressed if anyone can distinguish the difference in "salt taste", i.e., different salts, in a BBQ sauce, marinade or mop that also contains garlic, pepper, chiles, cumin, basil, thyme, etc.etc. from 0.1 percent of the salt.
Maybe, just maybe, some folks with a educated taste buds could detect different salt in a very delicate dish without any other or little seasoning, but I doubt it.
Personally, I don't know if iodine is harmful. I think for the majority of people it is not. I could care less at this point. One can find problems with any additive. Fluoride in the water may make me sterile (thank God!) ,or whatever it does, if I'm not careful.
I'll probably stir the pot with this post, but so be it. I would really like to give a blind taste test to those dudes selling this stuff at outrageous prices. (Actually I prefer "sea pepper over regular pepper" /infopop/emoticons/icon_wink.gif