Pisces say what they mean, mean what they say?
The trouble with your sign, if there is one, is that you can sometimes fudge the truth. You don't lie, exactly, but you'd prefer not to hurt anyone's feelings, with Neptune as your ruler.
You can also see all sides of a potential dispute, which is your blessing and your curse. Sometimes, it's hard to come down on one side.
The secret to great communication is to say what you mean, and mean what you say. Telling the truth as kindly as you can protects others from any meanness, while making sure you're staying true to yourself.