And yet taste tests show that even experts can't tell the different between the good stuff and cheap stuff they're told is the good stuff because expectation plays more of a role in what they perceive than taste does.
Master's of Wine certainly can. Quality is part of the test, as is the ability to tell variety and region.
From http://www.mastersofwine.org/en/examination/index.cfm
Practical - three twelve-wine blind tastings, each lasting two and a quarter hours, in which wines must be assessed for variety, origin, winemaking, quality and style.