As a landlord, I've had numerous replies from scammers to my rental ads. I now routinely ask all inquiries to tell me more about themselves before revealing anything, even my full name!!... if they are a scammer, more glaring spelling and grammer mistakes often appear in the reply... whereas the original email may have been canned and less prone to errors. Sometimes, their reply will hardly make sense at all, i.e. their questions do not fit with the property in your ad. I.e. one repeatedly asked about the "room" I was renting after I carefully explained that it was a house, not a "room".
I'm not averse to inquiries from abroad, since universities in the Baltimore area frequently attract people on sabbatical leave or foreign researchers, but some scammers can be pretty sophistocated. One scammer listed their name, a formal title and name of hospital in London where they presumably worked (believable in that there are so many med facilities in Balt.) .. in googling the hospital concerned, it turned out that it was a real one but the phone number given for it was fake, not even close to the right area code.
Most typically, the scammers are in a huge rush to move, want to send a deposit immediately and so request your bank info. Heaven forbid the day they get more sophistocated and learn better English.. it might be much more difficult to figure out who's legit. Googling the names on inquiries has thus far proved to be very helpful.

Jamie, these rental scammers ticked me off so much I decided to create a rental scam quiz so people could get a score and see if they are being scammed or not. Hope it can help someone.
http://www.rentvine.com/tools/rentalscamquiz/