Watch out landlords who cannot meet you personally, or are out of the country.
Those who ask for a wired transfer are simply scammers, whose methods are often alike.

Wire transfer
A central element of advance-fee fraud is that the transaction from the victim to the scammer must be untraceable and irreversible. Otherwise, the victim, once they become aware of the scam, can successfully retrieve their money and/or alert officials who can track the accounts used by the scammer.

Wired transfers via Western Union are ideal for this purpose. The wire transfer, if sent internationally, cannot be cancelled or reversed, and the person receiving the money cannot be tracked. In fact, that person often does not have to provide identification; they only have to know the identifiers of the transaction such as the control number and secret question. Thus, the overwhelming majority of scams involve making payment via wire transfer. Other similar uncancellable forms of payment include postal money orders and cashier's cheques, but as wire transfer is the fastest method, it is the most common. In many cases Western Union will not take any action against potential fraud and will not advise the police that a fraud has been committed or assist with out a court order. They claim there is no action they can take, and will not attempt anything to resolve this issue, including contacting the authorities in the country the money was sent to.

Source: Wikipedia Here is an example:

    I am glad you like the apartment. I will be back in August, 2010 which is why my contract expires here so you can rent the apartment for one year.

    However my initial plan was to swap the apartment out for another one here in Nigeria so i did not make provisions for viewing and so the keys of the apartment are here with me. Similarly i am not in Lebanon now like i said and so my bank account is currently inactive, so Western Union is the only payment method i can accept.

    You can call me on 002348067470507 so that we can further discuss things. As soon as you make a deposit payment i will send the keys of the apartment to you via DHL express delivery and it will reach you within 3 days, i will also provide a tracking no so that we can both monitor the delivery of the package.

    Let me know how soon you are ready to make payment as this will determine when you will receive the keys and move in.


Only the Receiver can pick up the money, right?
This is a brilliant scam. The need for confirming a cash transfer is ridiculous, especially if you think about it. But there is this whole perception of willing to take much less to get the right tenant. So you decide "hey, I'm just sending money to myself - what is safer than that?" The problem is that you've let this third party know all the pertinent details. Personally, I think that these money sending services in general don't provide much protection against fraud but here is the information about the little you need to pick up the money!
PS - I thought that the part about having the potential applicant to the apartment send a picture is clever too if you think about it.

The person Receiving the MoneyGram Transfer must present a valid photo ID and know information about the Transfer. Fraud perpetrators may suggest that a Transfer be sent with a relative or friend's name as the Receiver to show "good faith." The fraud perpetrators may be able to obtain valid-appearing ID to collect the funds. Sending such a Transfer is a red flag, and should cause concern about its being a legitimate deal.

Source: The Law .com

Nigerian Scam
A wealthy foreigner who needs help moving millions of dollars from his homeland promises a hefty percentage of this fortune as a reward for assisting him/her.
Here's how it works: Letters (or, nowadays, e-mail messages) postmarked from Nigeria (or Sierra Leone, or the Ivory Coast, or almost any other foreign nation) are sent to addresses taken from large mailing lists. The letters promise rich rewards for helping officials of that government (or bank, or quasi-government agency or sometimes just members of a particular family) out of an embarrassment or a legal problem. Typically, the pitch includes mention of multi-million dollar sums, with the open promise that you will be permitted to keep a startling percentage of the funds you're going to aid in squirreling away for these disadvantaged foreigners.

Source: Here is a Sample:

    From Mrs Rita Mesah.
    11,Rue des Jean Paul Deux-Plateaux Abidjan,
    Cte D'Ivoire.

    My Dear,
    It is my pleasure to contact you for a business venture which I and my Sons George and Henry intend to establish in your country.
    Though I have not met with you before but I believe one has to risk confiding in succeed sometimes in life.
    I can confide on you for the brighter future of my children since you are a human being like me.
    There is this huge amount of Eight Million united states dollars. ($ $8 million which my late Husband kept for us in a Security Company here in Abidjan Cote D'ivoire before he was assasinated by unknown persons.
    Now I and my Sons George and Henry have decided to invest these money in your country or anywhere safe enough for security and political reasons.

    We want you to help us claim and retrieve these fund from the Security company and transfer it into your personal account in your country for investment purposes on these areas:
    1). Telecommunication
    2). the transport industry
    3). Five star hotel
    4). Real Estate If you can be of an assistance to us we will be pleased to offer to you 20 % of the total fund.

    I await your soonest response.
    Respectfully yours Mrs Rita Mesah.
Source: The Law .com