Why did my grandfather-in-law salt his beer? My grandfather-in-law was born in England in the 1920s and fought in World War II. Somewhere along the line he acquired the habit of salting his beer before drinking it, which persisted for the rest of his life. I'm as curious about the cultural genesis of the practice as the food science of it – was there perhaps something about wartime beer that made it unpalatable without salt? I know there were other wartime food customs like bread and scrape so it doesn't seem implausible, but the "why" of this one isn't so obvious.
I can think of several reasons why you might salt beer:


Salt is a natural flavor enhancer, so you'd be able to taste the hops and malt more
Salt reduces perceived bitterness, so overly hopped beer would taste less bitter
The salt crystals may nucleate bubble formation, giving the beer more head (briefly)


I've heard of it being done before, but never with good beer, only low quality swill.  But then, since there were more quality problems with cheap brews at the time, this was probably a lot more common.