It’s not an old wives’ tale: People judge you when you make grammatical, spelling, or other mistakes in your writing. Just look at what the editors at Yahoo! Makers did:
Did the writer actually think that wive was a noun and therefore, its possessive form must be wive’s? Somebody needs to go back to third grade for a refresher: When the plural of a word ends in S (like, say, oh, maybe wives), its possessive just gets an apostrophe.