Then there's the Application Fee Scam. They charge you a non-refundable $50 per person, sometimes more, just to apply. In my case, that's $150, which goes to the Property Manager. So the property manager is motivated to take as many applications, and turn them down, as possible. They can easily make far more in application fees than whatever fee they collect from actually renting out the place.
After spending hundreds, only to get turned down within minutes ("Here's $150...oh, it's a No?), I learned to only deal with the person who OWNS the property, no property managers, real estate companies, etc.
Reasons for being turned down? Usually none given. Once it was because of my "criminal record" - a speeding ticket two years before. Goodbye $150.