Okay, I had a pure protein bar today and I saw that it said 19 carbs on the label but 3 net carbs on the front of the package, and it says for peoplet trying to watch there carbs count only 3...why is that? So what do I count 3 or 19?

Also, I had icecream cake yesterday and today and it was so good and has 27 carbs per serving...I was wondering, would this be bad carb, or does it matter?