I agree that the first line of defense against odor is to put deodorizer drops in the bag first. Then, your Glade Plug in won't have to work so hard.
You can purchase deodorizers at the same time you order your supplies, but they are pricey, if your insurance doesn't cover the cost. So, Shaz's suggestion of putting a capful of 3% hydrogen peroxide in the pouch after you empty is the most affordable and effective way to go. Mouthwash works, too!