When buying and selling on Dollars-Ad.com you have some level of trust in the buyer or the seller. Dollars-Ad requires a credit card authentication for all sellers and when communicating as a REGISTERED user. This authentication does not imply that the other party will be honest or fair in the transaction, only that they took the time and were found to have a a valid credit card.
Dollars-Ad does make it easy for people with a credit card to post items of all types on this site. The easiness in which items can be posted brings out people interested in scamming those people who are not careful.
Whenever you are in a position to pay for an item or a service, you should always be cautious when meeting the person and when evaluating the items or service. Dollars-Ad does not offer any creditability to the actual transaction, it is up to each buy to know what they are purchasing and any condition of the items or services.
When contacted by a buyer, they will emailing your person email, although the first time, they will not know your personal email the first time. As a seller you will be able to decide if you want to further purse the transaction after the initial contact. Scammers can be persistent, so be wary of those that send multiple contact requests in rapid succession.
Follow standards found on the FBI web site around Internet Fraud to help protect yourself, but in the end it comes down to your ability to judge and trust the other party in any transaction.