I've noticed a difference between modern democrats and modern republicans, and I'm of course speaking of the most vocal members of the party. Modern Democrats, beginning with Bill Clinton, will take the "good" ideas of the right, by which I mean those that are good for the moderate members of the country, and make them their own, I'm not saying Bill pioneered this, but he did learn valuable lessons from Ronald Reagan. Since Democrats are able to take the center they can point at the extremism that's left over. Thus attacks on republicans tend to be about the issues which they support, the war, taxes, etc. Meanwhile, republicans tend to be much more focused on moral issues, the idea of their morality is so strong that they are absolutely enraged when someone violates this moral code. Thus attacks on democrats tend to be about adultry, lying about sex, etc.
This is in no way implying that all democrats and all republicans fit into these catagories, just a trend I've noticed since Bush Sr. took office, feel free to comment.
Cheers