zillow hotpads etc How accurate are their Estimates

[Steven Maduro]

I was perusing my portfolio and 

took a peek at what zillow had them valued

I compared this with what the county had assessed as real value for tax purposes 

they were all off by 10,000   plus or minus from each other

my thought was that the county may inflate the value

but in some instances zillow was a bit higher than the county on a couple of properties

anyone else have a handle on how to read between the lines of these numbers

to get a quick guestimate. 

without getting to heavily involved with comps.