Washing a vehicle *with* salt?

So, I got some sort of gunk on my truck after parking under a tree for a few hours today. So I went to the car wand wash to try and get it off which was very easy since it was still very fresh and dissolved very quickly. Whew...

However, while I was there, a couple in the bay next to me was using a large can of Morton Salt with a sponge to wash their sedan. Curiosity overcame me, so I asked the guy why he was using it. He said with a straight face, that he was using it to get impurities off of the paint. I simply said that was interesting and thanked him for answering my question. Meanwhile, in my head, I'm thinking WTH?!?!

Has anyone ever heard of this?

 

One thing I noticed a couple of years ago on the label of Mequiars Ultimate Wash and Wax shampoo (the one I usually use)- one of the ingredients listed is "sodium chloride", i.e. salt. Always wondered about that.

EDIT: I got curious, scroll down to #3:
Car Shampoo: What Are the Ingredients? | DetailXPert's blog (detailxperts.net)

 

No, just no.

I've seen a couple drying their car with a roll of paper towels at a coin op car wash, might not be the best place to learn anything.

 

The only thing salt is going to dissolve is their car. I very strongly would not recommend this.

 

I just recently heard of the "clay bar glove". I must have been living under a rock. So much easier than a bar. Salt, terrible idea.

 

Yes, called it's called a Nanoskin Mitt. I love mine.

 

It is almost as good as matches or sliced bread.