QuoteI'm more inclined to just leave it on my plate uneaten but if asked, I absolutely explain, calmly and pleasantly, why I didn't eat it. If the server doesn't ask, I let it go and chalk it up to a learning experience.
IMHO, most restaurants want to and think they are sending out good product. I have trouble bringing to their attention that they aren't. Most of the time, tables around us are happily chomping down the same plate I am leaving. Usually I just chalk it up to my choosing the wrong restaurant.