Zillow data mining...value of amenities?

[Marian Smith]

Zillow says the highest sales price to list price homes had wheat colored kitchens...on average or some such. A fact(?) derived from their data mining. Have any of the data mining entities (zillow, corelogic, etc) put together anything useful to pricing? For example, what does an extra bedroom add to sales price? A third full bathroom? A pool in Austin, a pool in Amarillo, a pool in a neighborhood with a community pool, a pool in modest priced homes vs a pool in an executive home (do realtors even say that anymore?)? If there isn't a list, how do appraisers confidently add or subtract from comparable houses? Some kind of amenity replacement cost and neighborhood mean and % of total property value equation? Or gut? Thanks!