After the use of cleaning agents the smell of the solvents may remain inside the humidor. One should note that cleaning agents are only to be used inside the humidor in emergency cases. To get rid of the smell one might try the following:
First, the humidor should be opened and thoroughly ventilated.
If this does not help and the smell has not disappeared within a few days one may want to place a glass of whisky/brandy in the closed humidor. Caution: This will influence the flavor of the humidor for a long time! Some aficionados intentionally add a few drops of whisky or brandy to the humidifier liquid to refine the flavor of the cigars.
Thanks a lot to all customers of HumidorDiscount for their advice and suggestions.