It's often Bank Drafts they use. You lodge this bank draft, your account is bumped up. Fair enough says you, I'll now write this man a cheque or wire a transfer back to him. Money departs. In the meantime the bank has noticed that the bank draft actually has nothing to back it up. Unfortunately you don't get to say "But he said...", the bank draft is cancelled, your account is debited by the appropriate amount and he's got your money. Slam dunk so to speak.

A recent case in Ireland nearly had someone taken for tens of thousands in a similar scam, but the postmistress asked the scamee to check that everything was legit.

And why do people fall for it? Because people are greedy and dumb. What a wonderful world...