The current method of reporting sales experience on forums is open to spamming and manipulation since it is hard to show that a deal even took place. It is lik

The current method of reporting sales experience on forums is open to spamming and manipulation since it is hard to show that a deal even took place. It is likely that forums and merchants develop best practices to solve this problem. There is the potential that merchants will start to issue “proofs of sale” in a cryptographic form, that customers then use to make statements about the performance of the merchant in public forums. Could a blockchain or some other kind of public ledger be used to create a public sales rating record? I don't see how such a thing can respond to spamming and deliberate manipulation, however. Another thought I just had: could some combination of drones and self driving cars revolutionize dead drops?