Today a great example of one of the biggest issues with real estate web sites that allow the public at large to list properties for sale: the controls to prevent misinformation, misuse or abuse are very limited, making disinformation quite likely.
Today’s example: NBC Washington reports that 1600 Pennsylvania Ave is for sale.
Apparently Redfin imported this listing from Owners.com, a For Sale By Owner (FSBO) company, to their site. While Redfin no longer lists The White House for sale, Owners.com still does. Apparently this is a demo of their listing features but you have to read into the details to know that. Many of these type of sites allow practically anyone to advertise any property for sale or rent without verifying that the person posting advertisement has the authority to advertise it.
So what’s the big deal? MLS’s have specific rules and regulations for all listings in their database and all listings are inputted only by authorized users of the MLS. This closed system allows them to maintain the accuracy of the system through enforcement actions against violators. If the violations are egregious enough, the MLS’s can actually ban users from the system. Public listing web sites are nowhere near as well monitored or controlled. When I hear people say that Google or others are going to take over as the primary source of real estate listings I laugh a little; until a non-MLS entity finds a way to ensure reliable, consistent, and current information, their listings will continue to be met with some suspicion. While many agents (myself included) are posting our listings out to web sites such as Google, Craigslist and others, my MLS is still the only authority I check when I want accurate information.
What are your thoughts on MLS and non-MLS systems/sites?

