We had one appraiser in market who always had a hip pocket FSBO to pull out when he needed to justify some overvaluation. They would always be well above all the other market value indications from MLS exposed properties, and we all knew they had large seller concessions involved with them, however, in this nondisclosure state contract details & seller concessions are not typically disclosed to third parties. So, when a lender had something that didn't fit normal lending parameters (typically involving inadequate down payment & large seller concessions via some "equity gifting program"), they knew who to call, because he had a built-in database of non-MLS exposed properties full of seller concessions which he didn't bother to disclose. And nobody, absolutely nobody involved, would discuss anything about those situations, as to do so would implicate them & their lending pipeline in mortgage fraud. I confronted him about at one time, and asked him why people were consistently paying more for those FSBO properties than properties which were professionally marketed to a much broader audience via the MLS and he replied, "those are smart people, with extensively updated homes, who knew they didn't need to engage the services of a realtor to sell them ". I will always have a bad taste in my mouth over "FSBO's as comps" after seeing firsthand how the concept can be abused.