This technique can best be referred to as
dumpster dive.
The hungry and the homeless are not the only people who dive into dumpsters; criminals as well do to. Forms, for example, information from those cashed checks or transfers, bank account transaction history, wire transfer information or personal financial statement is available in dumpsters behind the bank or a utility company. A dumpster can be described as a
big bank in a big city where people like Sally can garner sensitive information in minutes.