Zillow doesn't pull old listings so you will see all these old foreclosure listings. It's mostly done to get noobs excited, from there they contact a realtor.
e.g
https://www.zillow.com/homedetails/46590-Chase-View-Ter-Sterling-VA-20164/68457645_zpid/
Currently still showing as active, "listed Time on Zillow
5556 days"