Call them con men, grifters, scammers or thieves. Or simply call them liars, because lying is what they do best. They stare you in the eyes, do it via email or over the phone, and lie through their teeth. They do it casually and with such conviction that we have no reason not to believe them.
http://money.msn.com/saving-money-tips/post.aspx?post=802849d0-ccb6-4a37-9be7-7698d83edde7