Republicans generally don't like their women uppity (read: independent, strong willed). For some reason, they hold out a special vitriol for women like Nancy Pelosi and Hillary Clinton - even though there are plenty of men who hold similar, if not identical, political positions. So when someone like Teresa Heinz Kerry comes along, who is clearly smart and doesn't take sh*t from anyone, they are particularly offended. Archaic thinking, if you ask me.
I also find the generalization offensive and inaccurate. First off, first lady is nothing more than a show position, and as such, the spouse, since she is not the one running for office, shouldn't really be attempting to abuse the limelight to dictate national policy; it's unavoidable to some degree, but it comes across as arrogant and self-absorbed for someone to think that her maritial connections alone qualify her to be such an authority. I would have the exact same opinion of Bill Clinton were he to act similarly if Hillary were to run for office, and I have the same opinion about Nancy Reagan's war on drugs agenda as I do about Teresa's attempts to hijack Kerry's candidacy into her own soapbox. I strongly disagree with Pelosi, Clinton, Feinstein, etc, but since they were directly elected (likewise if they were appointed) on their own merits, their public opinions and policy making stances actually have an aura of legitimacy. My, and I suspect other conservatives', unfavorable opinions of them are based more on their far left views rather than their gender. I don't see any centrist female Democrats evoking such strong reactions. In addition to that behavior, it's hard to like Teresa because she comes across as out of touch (being obscenely wealthy, but primarily because of marriage and not her own work), petulant (telling off a reporter isn't a big deal, unless you do it right after giving a speech on how badly civility is lacking in public discourse), and lacking self control. Laura Bush still speaks her mind and has her own personality, but she's much more subtle and controlled about it. In my opinion, it's easier to relate to her than to someone like Kerry's wife. Second, I am curious as to what grounds you would dismiss female Republicans like Elizabeth Dole, who was also a former Secretary of Labor and of Transportation, as ineffectual. I will also cite Kay Bailey Hutchinson, Christine Todd Whitman, and Olympia Snowe as other recent examples, all of whom were elected. Please don't dismiss them on some arbitrary grounds without actually justifying your reasons for doing so this time. Finally, while it is obvious that more women identify themselves on the Democratic side of the fence, that doesn't give the left a free pass to overlook its own attitude towards women. I read a lot of political forums and editorials and see just as much misogynist vitriol directed at Condi Rice as I do with Hillary Clinton. But since more women are Democrats, it's somehow OK to ignore the former while making gross stereotypes based on the latter.