These landlords want to only communicate via email (again, the language, grammar and spelling in their emails is terrible.) Usually the price on their listing is extremely low for the market - or sometimes free! The story they tell you is that they were suddenly transferred (again, usually to the UK or Africa) and they want someone to care for their home until they return. The catch? The keys to the property are still in their possession (overseas) and there is no one locally who can show you the property in their absence.
They encourage you to drive by and if you are interested, they have you fill out a rental agreement via email, sending a deposit (express mail a money order or cashier's check, or wire transfer money via Western Union or MoneyGram). Once the funds have been received, they will then send you the keys. Once that has been done, the Overseas Landlord has your money - but the keys to the property never arrive.