Never ever ever ever EVER send money via Western Union. If anyone asks you for this, 99% of the time it is a scam. Ask the landlord if you can view the property you are interested in with them. Judge their response, if they want money before meeting or before viewing the property, it is a scam.
Scams are everywhere - they are a huge problem on craigslist. Never send money - meet at the property with the person advertising the property. If they have some excuse why they can't meet you (they are in Africa on missionary work as an example) you can bet it's a scam.
This would be along the lines of the person who says you won money, they just need you to pay them to process it first. I have read so many posts about rental scams here my advice is look elsewhere for rentals.