Is money earned from commissioning the marketing of goods that may be used in ways displeasing to Allah permissible or forbidden, and does the marketer bear a sin for that?

There is no objection to marketing products from permissible websites and receiving a commission for that, and there is no need to investigate what the customer purchased. However, if the marketer knows that the commission is for a forbidden transaction (such as buying alcohol), then it is illicit gain that must be disposed of. But if he does not know, or if the buyer purchased something that can be used for both permissible and forbidden purposes (like a television), then there is no objection to benefiting from the commission. The sin of the buyer using the item for forbidden purposes falls solely on him and does not affect the marketer's commission.