Zillow Zestimates indicate a good flip?

[Brett Quelch]

For experienced investors and analyzers out there, when I have been looking at some potential flips, I found it interesting that some houses would be selling for $100,000 and redfin would be pretty close to that selling price, but Zillow estimates it for $200,000.  I'm guessing Zillow doesn't do work into knowing more about the house like redfin and is just doing it based of comp's in the area.  This got me thinking that it could be a good strategy to find a good deal for a flip.  For example, if I find a house for $100,000K listing and Zillow estimates its worth $200,000K, it seems like there might be a deal.  Am I missing something?