Can Muslims buy second-hand goods, keeping in mind the trader may be selling some stolen goods?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger. We ask Allah to exalt his mention as well as that of his family and all his companions.

Doubt that is not based on evidence does not prevent dealing in financial transactions. Actually doubt could be lifted by asking and inquiring about them.

Anyway, if the doubt which is based on evidence concerns the very thing to be purchased, the buyer must refrain from buying it and inquire about it, and if he finds out with certainty that it is forbidden because it is a stolen item or for other reasons, then it is prohibited to buy it because dealing with a person on something he does not own is unlawful. So, such a transaction is invalid as the seller from the two is disposing of something that belongs to someone else without their consent.

In case one was not able to remove the doubt (which is based on evidence) about the nature of the very thing to be purchased and he still has some strong doubts about it, after having done the necessary investigation and inquiry, then he is Islamically required to stay away from this doubtful transaction so as to take the safe side and be Allah-fearing when in doubt about a certain transaction, and that it is better, for the sake of his religion. For more benefit, please refer to fatwa 91177.

To sum up, doubt is of four kinds:

1 - Doubt that is not based on evidence: it is not to be taken into account.

2 - Doubt that is based on evidence, and after investigation and enquiry, it has become clear that the reason of doubt really exists; so this doubt is to be taken into account.

3 - Doubt that is based on evidence, but after investigation and enquiry, it has become clear that the reason of doubt is not existent; so this doubt is not to be taken into account.

4 - Doubt that is based on evidence, but this doubt could not be removed although having done the necessary investigation and inquiry, so it is better to stay away from this transaction so as to take the safe side and be Allah-fearing when in doubt about a certain transaction.

Allah knows best.