This depends on the property you are looking at. Is it waterfront? Year round? Lake rights? The equalization rate for the Town of Webb (Old Forge, Big Moose, Eagle Bay, McKeever, Stillwater) is now at 82%; however, we are in the process of a total re-val. Also, many of the assessed values in our town are incorrect. 50K is a good-sized reduction. The 10-15" less to which you refer is so variable on how badly the owner wants to sell.
Hopefully this has been of some help.