This is because juices are made with flavors that aren't exactly flavors as much as they are scents. When you exhale the vapor passes directly by the opening of your sinuses and you smell the vapor and get the true flavor of it. The vapor isn't able to do this on inhale. If you try exhaling
through your nose you'll really get the true flavor of whatever liquid you try. This is also the reason why people hold their noses when they eat or drink something that tastes bad, you can't get the true taste without your sinuses and nose being involved
EDIT: AC (assuming you are talking about atomic cinnacide) is a
juice that acts directly on the tongue. If you notice, try holding your nose and you won't taste any cinnamon, but you will feel that "cinnamon burn" on your tongue. This is also true for menthol juices.