Pink salt vs regular salt
In my experience, the difference between various salts has little to do with flavor, once you've moved beyond iodized table salt and bulk kosher salt, and assuming we aren't talking about salts that are flavored by additions like herbs or smoke during processing. 

So limiting the discussion to natural, high quality finishing salts, the differences are mainly texture and color. Some salts, like Maldon, are flaky, while others are large pyramids or cubes, and others tend to a small grain size and hold on to a bit of moisture. Each of these textures can bring something special to a finished dish. For example, flaky Maldon adds a delightful crunch, while another salt might adhere better to a French fry. 

Color, like the pink salt you mention, is used pretty much for the visual interest. And there is nothing wrong with that. Simply save it for a dish where it will be noticeable. For example, those pink grains would look amazing on a chocolate truffle, or a savory meringue.

If anyone thinks they can actually taste the difference among unflavored finishing salts, I'd challenge them to do a triangle test with those salts dissolved in water (in equal amounts by weight) so that texture and color isn't confusing the issue.