I suppose it’s possible that Mythbusters could have lied in an attempt to discourage people from sugaring tanks but I tend to think they’re just dead wrong; something that is not rare with them.
Back in the 80s a dealer I worked for took in trade a poorly running domestic (Ford or Chevy I forget which). He sent it back to service thinking it just needed a tune-up or carburetor work. When I determined it was the carb I removed the top and found the float bowl about 1/3 full of a yellowish-white substance.
Going back to the filler cap door I found traces of sugar all around the tank inlet opening. Verifiable by taste.
The boss called the people who traded the car in and advised them they needed to keep an eye on their new ride because obviously some neighbor was holding a grudge against them.
At least this car was fixed cheaply being a carbureted, mechanical fuel pump version.