Hmmm...I agree with you that many of the doubts expressed about Gov. Palin are sexist in nature. And that in a way this one is as well. But as a historical point, where I grew (in a very conservative corner of the industrial midwest) a popular bumper sticker read (paraphrase):

"I can't stand Pres. Clinton or her husband."

Obviously the underlying sentiment there was sexist as well, 'Bill Clinton is emasculated by his powerful wife'. But I'm just saying that I think Sen. Clinton's strong will and previous success did, at least in some parts of the country, cause people to question Bill's independence.