We don’t want to encourage you to directly trust the buyer if you don’t know them.
Trusting them would allow them to pay you, for sure, however, you might not be able to spend their tokens on something else, because other sellers might not accept these tokens. (Since you would get their personal CRC – See the question: How do you mean each user has their own, personal tokens?.)
Better to trust more people within your network: real people you know and you consider trustworthy. That will increase your personal and indirect links throughout the trust network, because your peers are connected to other peers and this will bridge the lacking connection with the buyer.
If you know the buyer, however, you can trust them directly.