In general, good real estate photos are bright, slightly above eye level looking slightly down and furthest wall-to-furthest wall without distortion at the corners.
The thing I commonly see are lack of attention to details and that's where a photographer who has shot a lot of houses will really help.
I don't typically shoot real estate, but in one particular circumstance I did and took a well lit shot of a living room with the skyline in the background. There was an ottoman in the center of the room set up with 3 magazines fanned out.
The problem? I opened up the files in photoshop and noticed the magazines were Macleans magazines. Great publication, but too bad the 3 covers had Hitler, the Pope and a Canadian flag on them. I facepalmed for a good minute.
This site is good for a laugh for bad photos:
http://lovelylisting.icanhascheezburger.com/