Please be aware of the following fraud schemes:

The Nigerian Fraud Scheme.

Individuals in Nigeria or other West African countries will often respond to ads placed on various classified web sites on the Internet about the sale of autos or other large ticket items. (The individuals will often claim they are from Scotland or another country outside the U.S.).
Typically they agree to purchase a vehicle and will then forward a counterfeit cashiers check to the victim in amounts exceeding the agreed upon purchase price. The unwitting victim contacts the buyer concerning the overpayment.

The victim is usually instructed to wire funds via Western Union to Nigeria or another West African country. Funds are usually wired before the counterfeit cashiers check is returned to the bank where it was deposited. This results in vehicles being shipped without payment and the victim is out additional money spent on the wire. In every instance the bank will pass the loss back to the individual who deposited the counterfeit check.

Nigerian letter frauds

These Individuals will also make use of the system's abilitiy to allow anyone to respond to classified ads, they contact users with one of hundreds of variations of this schemes.
The Nigerian letter frauds combines the threat of impersonation fraud with a variation of an advance fee scheme in which a letter, mailed from Nigeria, offers the recipient the "opportunity" to share in a percentage of millions of dollars that the author, a self-proclaimed government official, is trying to transfer illegally out of Nigeria.
Click Here for more on this and other Internet frauds schemes.

The FBI, Secret Service, and other government agencies are well aware of this fraud scheme.

See the following links:

Secret Service Warning
FBI Warning

This fraud scheme should not deter users from using the Internet as a place to sell and buy goods. Users should feel completely safe in placing classified ads, but should use wisdom in offers they receive from interested parties. And remember, if it sounds to good to be true, it probably is!

NOTE TO CONSTRUCTION INDUSTRY CLASSIFIEDS USERS:
If you are a user of the Construction Industry Classifieds and someone has approached you in the above manner, please let them know that you are not interested (or just ignore their offer) and please know that your Email address and other information is not accessible to anyone unless it appears as part of your ad listing.