Ben Smith recently had a post that was linked on Drudge. The subject of the post was a picture of New York's junior Senator wearing a cross; it engendered 863 comments as of this writing.
I had an email exchange with EnWhySeaWonk on the subject, which he blogs about here. The argument, which I think deserves consideration, is that Hillary is so hated by the right that a possible run by her for the Presidency is essentially stillborn. He goes further than I would, speaking of the risk of assassination, but the hatred is there. So what does it look like?
On the assumption that the universe of Drudge Report readers can be considered indicative of the opinions of the extreme right, I just spent two miserable hours taking a look at how they hate Hillary. It's ugly.
Concepts and attributes, as applied to Senator Clinton personally:
References to/comparisons with Lenin, Hitler, Stalin: 17
References to Satan, the Anti-Christ, vampires or other demonic creatures/forces*: 61
References to Atheism, Socialism, Communism, Nazism, Freemasonry, "Far Left", generic totalitarianism**: 53
References to whore, slut, lesbian, "cross-dresser": 18
References to Vince Foster, Ron Brown***: 12
References to hypocrisy, lies/liar, calculating, pretended Christianity: 132
References (negative) to flag-burning amendment and other pro-right positions taken by Hillary: 6 ****
Sum: 293
References (positive) to flag-burning amendment and other pro-right positions taken by Hillary: 0
Comments supportive of Hillary: 53
Sum: 53
And here's a graph:

Not sure what to make of that, if anything, but if this thread is any indication, the right truly, deeply, irrationally and viscerally hates Hillary Clinton. This shouldn't be news to anyone familiar with their uncensored message boards, or who lived through the Clinton Presidency; but if anyone thought that the passage of time has taken the sharp edges off, they are truly and sorely mistaken.
Notably, the majority of these comments does not express disagreement with any concrete policy proposal. They are personal; witness the references to demonic entities or Hillary's alleged dishonesty/pandering/lack of sincerity. Some are based strictly on false information, such as the references to Vince Foster. The question is whether this kind of sentiment will be erased, or even neutralized, by any amount of positive campaign ads.
Put together, all of this adds up to a very potent cocktail of fear and loathing. It's just one thread on a New York City blog, in a small, lonely corner of blogdom, but there's no reason to suspect that this was anything other than a spontaneous explosion of genuine, unabashed hatred. How that would translate into the real world of the 2008 election is anyone's guess, of course.
* Includes comments that refer to supposed attributes of the above, such as crosses burning the flesh of demons, etc.
** Includes terms for the relevant ideologies and their adherents, i.e. "Communism" and Communist", as well as the adjective form, "communist".
*** Members of the Clinton administration whom the far right claims (despite multiple investigations proving otherwise) were murdered by the Clintons.
**** The context of these indicates that they reflect left-wing, as opposed to right-wing, antipathy