The FDIC updates known counterfeit Cashiers Checks by name and bank location online.
If you as a seller receive a bank-type Cashiers Check, you may want to view these pages from the FDIC to read about known fake cashiers checks in circulation:NOTE: YOU NEED TO COPY AND PASTE THE LINKS BELOW BECAUSE EBAY DOES NOT ALLOW LINKS N THEIR GUIDES)
(the above link is for 2008)
(the above link is for 2009)
For Canadian and USPS Postal Money Orders, please see this eBay guide: