Beware of currency exchange offices, especially in tourist areas. The folks at Honest Guide went to Florence Italy and spoke to people who exchanged U.S. dollars for euros and got ripped off.
One American they interviewed exchanged US$1000 for 653 euros (US$741). That's because the office charges a 19.9% commission and a 9.9 euro fee. If they'd exchanged their money at the post office they would have gotten 820 euros (US$931).
The host of Honest Guide also interviewed an unapologetic cashier about the terrible rates, and tried to interview the head of the company but he refused to speak with them.
The Honest Guide folks also made a video about five tourist scams in Italy, included the "deaf-mute scam," the "wristband scam," "illegal sales," "rip-off restaurant prices," and the "painting scam."