“Have you ever gone to a restaurant and ordered a Coke, then taken a sip and realized what’s actually in your cup is Dr. Pepper? You don’t hate Dr. Pepper. In fact, on any other day, you might very well love an ice-cold glass of its wonderful fizzy sweetness, but on that day, you wanted Coke, and Dr. Pepper tasted awful.
“The audience you’re trying to reach with your writing is no different—they want their expectations fulfilled—and today, we’re talking about how authors can best accomplish that goal.”
Source: Editor’s Corner: The Author’s Toolkit: How to Set—and Fulfill—Reader Expectations