We used FeBreeze. Well, we went to a dollar store and used their brand of Fabric refresher. We set up the tent, sprayed it down heavily and did this for three days in a row. But it worked!
I've also used a scented disinfectant (the kind in an aerosol can) before too to kill the mold and mildews that cause the odor in the first place.
Also, don't put your tent away wet. If you really have to, the first sunny day you have set it up again and leave it a few days.
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