The carpet is one of those things in our house that absorb a lot of dust and different smells. To make it fresh and clean between professional washings, you can use baking soda. Sprinkle the carpet with a good layer of the powder and let it rest for 15-30 minutes. In case there are very bad smells, you may wait even until tomorrow. After that just vacuum the carpet to get rid of the soda and the smell too.