Here is an interesting article supported by data, from Quicken Loans about the increasing gap between what homeowner's think their home is worth, and what an appraisal says it is worth.

http://www.quickenloans.com/press-room/2016/03/08/homeowners-denial-difference-between-expectation-and-appraised-value-reverses/#ksjkriiMPTToP3Jl.03