Is the profession of fumigating commercial shops with unclean clothes, carrying an instrument to ignite the incense, and receiving payment for that, forbidden?

Fumigating the premises is permissible if it is done with the owner's permission and consent, as it falls under the category of leasing a permissible benefit. It is stipulated that the rent must be known. If an explicit lease contract is not concluded, it is overlooked, and the customary rent is given. This is analogous to buying and selling through mutual consent, and the permissibility of a laundryman or tailor working without a contract if there is a custom regarding payment, and entering a public bath, riding with a sailor, and employing a porter, a witness, and the like.