Zillow Recently Sold Properties

[Barry Pekin]

So I was searching Zillow for recently sold properties.  When I went in there, I decided (among other things) to list those properties from low to high purchase price.  There are several at under $1,000, and several more under $10,000.  This is in Loudoun County, VA, where there's lots of money.  I'd like to know if these prices/sales are legit.  Does anyone have experience with this?
I just picked one that said it sold on 6/10/17 (over two years ago) for $2,900, where the Zestimate is $659,000.  I looked it up on the county website, and there's no such sale recorded.  It shows the last sale on 8/27/04 for $647,000.
My question is, has anyone else done this, and are those records on Zillow normally accurate?
I'll do more research (maybe the low prices are anomalies) and see what I find, but in the meantime, I was curious as to what other people have experienced.