You can't be objective if you know what you're tasting – you can be professional, but you have a preconceived notion of what's in that glass, so its simply not possible. So Gary V. and Parker are out. As an aside, I assume that Jay Miller and the others at WA also do not taste blind – am I correct? What about IWC?
Either way, count me in no one is objective camp. Mostly, a blind taster might not know what exact bottle he or she is tasting, but its hard not to know a lot about the wine, including a pretty good estimate of price point or at least this is/is not a <$25 wine.
Further, after drinking wine for roughly a decade and really getting into it about 3 yrs ago, I can pick out some producers and/or wines blind. I can only assume these guys do it far more regularly. In this vane, Parker's famed memory almost makes it pointless for him to taste blind – he's going to know so often, he might as well make sure his preconceptions are accurate.
Blind tasters can do everything to keep preconceptions out of the score and notes, but a professional has to know too much about what's in the glass actually to have no preconceptions. And then there's the advertising and the socializing with wine people, and the flame fest when you pan hordes of Opus One fan's favorite wine. So again, no one is objective.
I guess if you never left your house or watched/read/listened to modern media while training yourself to be a wine expert by having de-labeled and re-bottled wines (those Turley bottles would start to be recognizable) delivered so you know only vintage, region, appellation, etc., then you could claim to have accomplished what would seem to be the holy grail of wine tasting - be an "objective" critic.
Incidentally, the one critic that I think might have somehow accomplished this is Laube, because his Cab scores seem to have no bearing whatever to price and producer and little relation to prior track record. Before anyone thinks I'm being facetious, I don't drink enough Cab to have anything but an anecdotal opinion, but I have found many of his ratings on bottles I have had to be spot on, especially the few bottles I've had from the 1996 and 1997 retrospectives.