Misuses in writing that involve apostrophes (or the lack thereof) scream for attention, especially to editors. Oddly enough, most involve homonyms—words that sound the same but have different spellings.
Consider "I really like you're poem," for example. Or, "Its really tough to know which word to use."
The error of using "you're" for "your" is often committed in the heat of writing, in part because the words are homonyms. They sound the same, and the part of the brain that processes words to text sometimes just sends the first word that sounds right to your fingers. To complicate matters, when you reread what you’ve written there’s a good chance you’ll see "your" where you wrote "you're" (or vice-versa).
You may end up looking stupid when an editor reads your manuscript—or at least wincing when you discover the error later. You can cut down on this sort of problem by using fewer contractions.
A similar problem occurs with “its" versus "it's." If you’re one of the world’s many self-appointed proofreaders, you know that the wrong choice is made far too often in advertising, letters, or anywhere else someone is faced with the question, “Should I use an apostrophe here, or not?”
The problem can plague even experienced writers. It’s the homonym effect again, complicated by the fact that we are trained to use an apostrophe with almost every possessive.