I believe both the original poster and the "prom king" camp are correct. Yes, it is true that B. Clinton and George W. Bush were (in their first terms) elected in part by a tidal wave of goodwill of the sort related to proms, beds, and beers.
However, just because it was the case for these men does not negate the possibility (and, I believe, fact) that H. Clinton is suffering from disproportionately more stringent "likeability" factors laid on her by virtue of her gender.
As a person who at this stage is open to voting for any candidate from either party whose policies and articulation of them impress me the most, I must say that Obama and Edwards were off the mark in their treatment of Clinton during that debate. OP had it right: it was wholly inappropriate for Obama to engage with her in this "are you likeable?" issue, and equally inappropriate for Edwards to continually, throughout the campaign, harp on her attire.
Every issue that can possibly be used to denigrate a woman seeking power has been pulled out in the tackiest of fashions:
Physical appearance (via photos)? Check.
Age or Aging? Check.
Clothing style? Check.
Likeability and warmth? Check.
Tears or other symbols of presumed "weakness"? Check.
If I were the type of person who voted in a reactionary manner for people being unfairly treated, Clinton would be a lock for my vote.
As it happens, I continue to watch the campaigns unfold and hope the gender- and skintone baiting can come to an immediate end, so we can focus on the substantive issues.