Also there are some borderline issues with taxes (and/or self employment or small corp) that can give you problems. (One for example is deducting for a home office, another might be charitable deductions, another might be writing off some auto usage).
Think in terms of what happens when you see the flashing lights of a police officer in back of you. Even if you haven't been speeding you don't automatically think "no problem I didn't do anything wrong" you get anxious thinking there might have been some mistake that you have made.
 See the typical business owner isn't Zuck and doesn't have an army of knowledgeable advisers to handle all the details. You are essentially on your own with your accountant.