If there have been enough new comps in the area you're talking about to justify the value the appraiser found, then the appraiser is not doing anything wrong. The problem lies with the bank that is choosing to fund the loan, in my opinion.
Example: A neighborhood in Chino called The Preserve has resale homes (98% are REO & short sale) & are sporadically selling brand new homes. The appraisers must find "Like" new homes to compare them with & the banks are accepting this practice. This IS a problem because the same sized home that's selling down the street as a resale / short sale, many are in the same perfect condition with all the upgrades like the new homes,,same sized homes are selling for as much as $120K LESS.
So, the second that buyer, buys the new home, moves in & goes to try to resell in 6mos (they likely won't do that, but if they did) the home will comp out as another Resale home & they've got Instant Negative Equity.
Banks are further creating a mess for themselves. Don't blame the appraiser, but the banks' acceptance of the methods in which they appraise.