Zillow.com, a real estate valuation website, receives more than 4 million visits each month. In Denver, 54 percent of the homes listed on Zillow have been viewed. Zillow allows consumers to see what their home is valued at, their neighbors’ homes or even their boss’s. Just go to Zillow.com, type in an address and a wealth of information pops up. But some experts, in Denver and across the country, say they have doubts about some of that information.

“Some of the estimates offered by Zillow.com only claim to get within about $100,000 of the true price,” wrote Elizabeth Razzi in her book, The Fearless Home Seller. “Well, a Magic 8-Ball has that kind of precision. Is $435,000 the right price? Shake, shake, shake. My reply is no. How about $535,000. Shake, shake, shake. You may rely on it.”

The biggest differences appear to be in older Denver neighborhoods. “They’re probably very good in the suburbs, where you have several models that are identical, it probably is very good,” say local brokers who say its frustrating because Zillow estimates have led to low-ball offers.“They think that Zillow is so authoritative, when the truth is individual properties are so different.”

A spokeswoman for Zillow said the company is only as good as public records. Homes in older Denver neighborhoods are notorious for being inaccurate, especially since many people 25 years ago did things such as add living space to houses without pulling permits. “Obviously, no one from Zillow has ever been in these houses,” she said. “We don’t know that you might have put in a new kitchen or bathroom, for example.”

Zillow created My Estimator so a homeowner can input improvements and correct errors. Some brokers don’t like that feature because they think homeowners could exaggerate. Zillow emphasizes it is a “starting point” and is no substitute for a real estate agent or some other expert who is familiar with a particular market.

John Skrabec, principal of Live Urban Real Estate, said some house hunters trust Zillow to be more accurate than it is. “I hate Zillow,” Skrabec said. “It has gotten so much positive press, but the truth is, their estimates are often way off. Some buyers will say, ‘But Zillow says it is only worth this much.’ It can be very frustrating and is another obstacle Realtors have to deal with.”

Also, some people might not even consider a home because by Zillow’s estimate it is vastly overpriced, even though it may be very reasonably priced for that specific street and neighborhood, he said.

Excerpted from an article original published in the Rocky Mountain News.