I think you guys are making it way too complicated... It's a common scam (in Europe) where you find somebody who sells something online, that only works with bank transfer (second hand stuff or a trader that does not take credit cards). You tell him you seriously want to buy his EUR 100 cucko clock but you have a new bank and as you are not in the same country, you want to do a test transfer first to see how much money the bank is keeping as a fee for a cross border transaction (IBAN is free but for example some French and Greek banks still charge a fee). You tell him to look for the two deposits and he will tell you.

No keylogger or dumpster diving required....

As the guy is happy to see money arrive onto his account, he is not suspicious that he will get scammed later.

(as seen on Dutch TV http://www.opgelicht.nl/dossiers/detail/paypal/ )