I have a thing of Trader Joe's delicious Tomato Bisque soup that was accidentally purchased as the low sodium version. More or less, they try to replace sodium with potassium. Now I don't know much about gustation (the sense of taste), but I do know that if my body were easily confused about the difference between sodium and potassium, I would be fucking dead.
Everything, from the function of my nerves, to my cells, to my freaking heart are completely dependent on my body's exquisite ability to tell the difference between those two ions. It is the crux of all of life. This isn't shitty sorbitol, Soup, this is ionic gradients, the foundation of cellular survival.
There is even a sodium/potassium pump in every single biologic cell. This thing takes sodium, and pumps it out of the cell, and at the same time, brings in potassium. It knows the difference so well, that it can let 2 of one in, while pushing 3 of the other out. It's the racist bouncer of the body. And to say you might slip one K+ by, disguised as a Na+, would be like saying, oh yeah, Oxygen and Carbon Monoxide are pretty similar, my body won't know the difference.
And yet this low sodium variant is so bold as to think that it can trick my tongue, and a few billion years of evolution, into believing I'm having awesome soup and not mediocre soup.
But I trust you Trader Joe's, so let's do this.