Originally from the sixth issue of the excellent Lucky Peach magazine, mad food scientist Harold McGee of the joys of aging canned food and its "extremely cooked flavor".
This punishing heat treatment helps create the distinctive flavors of canned goods. So does the hermetically sealed container, which means that after any preliminary cooking outside the can-tuna is steamed to remove moisture, for example, and the best French sardines are lightly fried-oxygen can play only a limited role in flavor development, and that whatever happens in the can stays in the can-no aromas can escape. Hence the common presence of a sulfurous quality, which may be eggy or meaty or oniony or cabbagy or skunky, from compounds like hydrogen sulfide, various methyl sulfides, and methanethiol. Some of these notes can gradually fade during storage as the volatiles slowly react with other components of the food.
The overall flavor is nothing like freshly cooked foods. Food technologists often refer to it as "retort off-flavor." But it's only off in comparison to the results of ordinary cooking. It's really just another kind of cooked flavor, an extremely cooked flavor, and it can be very good. Canned tuna, sardines, chicken spread, and Spam all have their own appeal.
In last Sunday's episode of Mad Men, Grandpa Gene ate ice cream right out of the container and salted each spoonful before putting it in his mouth.
It was an odd sight...salt isn't normally the first thing you think of as an ice cream topping. After the episode, Rex Sorgatz tweeted:
WHO THE FUCK SALTS THEIR ICE CREAM?
Salt has its own flavor when it's concentrated (if you salt foods too much or eat some all by itself) but used judiciously, salt takes the natural flavor of food and enhances the intensity. To use another dairy product as an example, fresh mozzarella tastes pretty good on its own but throw a little salt on top and it's mozzarella++. Salt makes ok food taste good and good food taste great. Along with butter, salt is the restaurant world's secret weapon; chefs likely use way more salt than you do when you cook at home. It's one of the reasons why restaurant food is so good.
But back to the ice cream. As food scientist Harold McGee writes, salt probably won't make ice cream taste sweeter but will make it taste ice creamier, particularly if the ice cream is of low quality, as the store-bought variety might have been in 1963.
I'm not sure that salt makes sugar taste sweeter, but it fills out the flavor of foods, sweets included. It's an important component of taste in our foods, so if it's missing in a given dish, the dish will taste less complete or balanced. Salt also increase the volatility of some aromatic substances in food, and it enhances our perception of some aromas, so it can make the overall flavor of a food seem more intense.
So that's why the fuck someone might want to salt their ice cream.