Dr. Muzammil Siddiqi, former president of the Islamic Society of North America, states the following: “In Islam it is permissible for the buyer to make a condition that he will return the merchandize if not satisfied within a mutually agreed time. This is known in Fiqh as ‘Khiyar Ash-shart.
It is reported in a Hadith that the Prophet, peace and blessings be upon him, said, “When you buy something, say to the seller, ‘No deception.’ Then you have a choice for three days either to keep the item or return it to the seller.” (Reported by Ibn Majah).
The jurists maintain that the seller can extend this period. If the seller agrees to take it back after use also, it is his choice. So basically, there is nothing wrong in this transaction as long as it is mutually agreed to by the buyer and seller. However, it is un-ethical to misuse this option. It should be used only if one is not satisfied with the item for some reason. One should not buy the item with the intention of using and then returning, because that is not the purpose of this option.
We should also keep in mind that for big stores this is a kind of advertisement. In this way they attract many customers. So the more the customer misuse this policy, the more the merchants will charge. And finally, it is the customers that will end up paying for every thing.”