Per Inman News article
Zillow, and other third-party real estate search sites like Trulia, have made a big push to get data feeds directly from brokers and MLSs because, without a direct feed, the portals face accuracy and timeliness issues with the listing data they get from a variety of sources.
A recent study by the brokerage and referral site ZipRealty, for example, showed that 16 and 17 percent of the homes listed as for sale on Zillow and Trulia, respectively, in the markets the study looked at were not listed as for sale in the MLS.
The point here is when you are ready to get to work on your buy/sell activity, there is no substitute for a licensed flesh and blood brokerage that has access to info you need – when you need it.
Ask me about the house valued $184k then $93k just after, and all in the same year, I’d sold it for $150k! The seller kept pointing out the similar house listed a block away ‘Zillowed’ at $160k that eventually sold for $85k. Zillow has no eyes.