1. Anywhere where cruise ships are regular visitors. There are often free meals on the ship, and obviously no overnight stays in hotels.
2. Anywhere popular with young tourists (Amsterdam, Berlin etc). This might be limited to Europe, with a €20 flight (or bus) to the city, a bed in a cheap hostel, a visit to all the free things etc. This isn't new, but Couchsurfing and cheap transport have probably increased it.