A method for preventing an unauthorized transaction indicative of scalping includes: receiving transaction data for a first payment transaction including one or more product identifiers associated with one or more products purchased in the first payment transaction and consumer identification data; updating a consumer profile based on the one or more product identifiers, wherein the consumer profile is identified using the consumer identification data; receiving a transaction message for a second payment transaction including at least one product identifier included in the one or more product identifiers and at least one consumer data value that is also included in the consumer profile; determining a suspicion score for the consumer profile above a predetermined threshold value; and transmitting an authorization response message for the second payment transaction including a response code indicative of rejection of the second payment transaction.