It is worth pondering this term, which means a literate person who offers unsolicited corrections of the spelling and grammatical errors of others. The use of this expression opens onto the question of what sort of unsolicited advice is socially acceptable and what isn’t. Picking holes in another person’s language pushes emotional buttons because the development issues that have limited a person’s literacy are so back in time that culpability is diminished. But there is plenty of unsolicited advice offered on dietary or fashion or political choices, and these are less likely to attract the unkind comparison with the National Socialists. But it’s probably only a matter of time I suppose.