What Idiot determines the value of the homes on this thing?

The Zesimate is not an appraisal or market value. All Zillow can see is numbers. If your assessment, purchase price, sales price when you sell or price trend for your house specifics is not higher, then Zillow cannot see any of your improvements. Not only do they not account for landscaping, they also do not consider views, waterfront, ugly houses, granite, houses with bad neighbors etc.

The Zestimate is what it is. It does not pull your house value down. Buyers will decide what they are willing to pay for your house, not an agent, an appraiser and not Zillow. Real estate is still the free market and in that market the buyer decides. If you want a value on your house, I would contact a local agent in your area. They can gettyou the most recent sales and give you a ballpark estimate based on your specific upgrades and the local market.