Prudential Rubloff Realtor Eric Rojas, at his Chicago Real Estate Local blog:
My personal opinion is a for-sale sign won’t help sell your condo. In my years listing property not one qualified buyer has called on a for-sale sign on a condo building fence and then bought the home. Occasionally you will get calls from curious people for any number of reasons, nor are they seriously looking for anything to purchase. It’s an inefficient way to shop for a condo and rarely if ever practiced.
Signs are more effective, however, on single family homes or small multi-unit buildings where serious buyers of those types of properties can identify with the home driving or walking by. In the city, there are fewer single family homes for sale in many neighborhoods. A sign going up in a hot neighborhood can help attract real buyers that know the location and average price of homes in the area. Still, if the price does not meet market expectations the home won’t sell no matter how many showings a sign attracts.