Chris Higgins of mental_floss wrote a book called The Blogger Abides. It's about, you guessed it, blogging! In an excerpt he posted today, he gives many examples of misused words and phrases he's been called out on over the years. A couple of examples:
Tough Road to Hoe
A lot of idioms don’t seem to make sense, particularly if you (like me) never really heard them right, and just said what you thought you heard. It’s “a tough row to hoe,” not “a tough road to hoe.” Hoeing a row is something you do in a garden. With a hoe. It’s tough. You don’t hoe a road. I think maybe I thought it was “a tough road a-ho” for a while, which also seems to mean nothing (unless perhaps that’s short for “ahoy”), but maybe in some old-timey slang from my primitive brain it means something…anyway, pro tip: when using some seemingly nonsensical idiom in your writing, Google it first to figure it out what it really is and how to write it properly.
The word “plethora” traditionally has a negative connotation–so you’d say something like, “I’m pretty sure she’s crazy because she owns a plethora of cats and also never wears shoes.” In modern usage it’s often used much like “myriad,” just meaning “a lot of something”–but some readers will freak out, because of its traditional use as “a problematically large number or amount of something.” Further, the word myriad actually has a positive connotation–so you’d say something like, “Myriad stars shone from above.” (Note: debate rages over the possible uses of the word myriad. In the example just now, I used it as an adjective. It may also be used as a noun, just like plethora: “A myriad of stars shone from above.”)
In short: myriad good, plethora bad (due to quantity).
There's plenty more, from the obvious to the totally confusing. Link