Either a refinance or purchase loan requires a full appraisal by a licensed appraiser. Sometimes the value on an appraisal is different than what the borrower is expecting usually less than the borrower needs to get a loan. Becoming an appraiser is not that easy. Basically there are courses to pass, 2,000 supervised hours to complete, appraisal tests to pass to become licensed and more to be certified. Every few years they need to complete continuing education. There are professional memberships to join, and criteria set up by its professional association and lenders. Some unhappy borrowers want to dispute the value on a property established by an appraiser and generally cite Zillow or some other website, a real estate agent or note a home sold in the area they know about. Given the fact it generally takes 5-8 hours to complete an appraisal and all the comparables need to be explained, the unhappy borrower has no merit. If a borrower is unhappy with an appraisal they should pay for another appraisal, another appraiser will work within the same guidelines required by the lender of the loan the borrower intends to qualify for to establish the value. Chances are, the new appraiser will come close to the same value as the first.