I leave salt deposits on my shirts on really hot summer days, and after exercising my BF often says I taste like a french fry. So yeah, I think being salty is a pretty common issue for CFers, even to the point of visible or uncomfortable salt deposits on our skin. It's not anything to worry about -- just make sure to eat or drink something with sodium to replace what you lose!
I'm guessing it does correspond to sweat test scores b/c, after all, your sweat test results are an actual measurement of how much salt you sweat out during the test. So people with higher scores are going to be more likely to get visible salt deposits, etc. since they are obviously sweating out more salt. But I also think it can change over time -- many people were sweat tested as infants or very young children, and I believe there is actually a lower standard for infant positives b/c infants don't sweat as much. So you might have had a lower score if you were tested earlier and now you may have lots of salt on your skin. I'm not sure if that's accurate, but it is my understanding.
My least favorite part is in the summer when I lick my lips or something like that, my tongue burns from the saltiness of my lips and mouth. Yuck. I also tarnish silver jewelry really fast b/c of the salt deposits and once ruined a leather jacket by sweating salt onto it. My horses used to LOVE to lick me, and my dog still does. I think I'm like a walking salt lick to them. I also notice my tears are extra salty, which I've always found interesting -- maybe it just mixes with the salt on my face after leaving my eyes? Or maybe tears are like sweat with CFers? No idea there.
My infant is really salty. I call him my little french fry. He wasn't salty until about a month old. In fact, I used to lick him (weird I know) to see if he had CF since that is sometimes the first clue for babies, and we found out during pregnancy that we were carriers.