Salt will act to modify creosote to some extent but what it cannot do:
-mechanically remove the creosote uniformly and predictably
-inspect the chimney
-report the condition of the chimney and suitability to the homeowner.
That goes for those sweeping logs, too. Then you have some of the old classics:
-send a goose up the chimney flapping his wings. Once he's done, you cook him!
-Burlap bag full of rags or junk pulled up by rope
-Christmas tree pulled up chimney. Great fun when the tree sticks half way up!
You could try the old English method but I'm guessing you would get in trouble for sending an underfed little boy up the flue with a hand brush and and scarf for a respirator. FYI: the first case of occupationally linked disease was scrotal cancer in chimney sweeping boys noted by an English surgeon. Most boys didn't live past their 20's. Polycyclic Aromatic Hydrocarbons (PAH) are carcinogenic.
Then there is the other classic where you call in a chimney fire to the fire dept. and light a bundle of newspaper on the smoke shelf just before they get there. They drop chains to knock the creosote loose and you get a free cleaning....
Salt will accelerate corrosion of the chimney and is not recommended. Nothing still beats proper mechanical brushing and professional inspection.
I heard the salt one from my grandparents and I was born in S.C..