As a good example of my linguistic hypocrisy, I note the pronunciation of mischievous. I have long stated that spelling and etymology are only guides to language, not rules, and whatever native speakers of a language, or if you are fussy - educated, intelligent speakers of a language - say is correct. All other distinctions are markers of class, region, or at most, examples of usage in inappropriate context. That is, the situation required a more formal diction or expression which the speaker neglected. But even that is social convention.
But I cringe whenever I hear the pronunciation mischeevee-ussly. There's no "i" in that syllable, dammit. Today I heard three intelligent, educated professionals use that pronunciation.
They're just wrong.