For me, watching Bush debate is a lot like watching my son play baseball. While I may root for him to do well, I feel helpless in being able to make him do well.
Like when my son is batting, I try to will it that he'll hit the ball. Similarly, while observing Bush, I try to will it that he'll nail a point.
So when Kerry says lamely, "I consider nuclear proliferation to greatest threat to our nation." I'm using all my mental energy to try to get Bush to say something like "Well Senator, I consider going after the blood thirsty terrorists who are trying to murder Americans to be our top priority."
Bush isn't as quick on his feet as Kerry. Kerry, a former prosecutor, is in his own in having to put together a compelling argument on the fly. Bush defeated Gore in the 2000 debates because Gore came across as a haughty lecturerer. Kerry won't make that mistake.
One might argue that Bush lost the debate on style -- which is what really matters but won it in terms of substance. Bush's arguments are stronger IMO but he isn't able to put those arguments forward in a compelling way.
Kerry's Iraq position is incoherent. Idealogues on the left may be content to parrot the line "Kerry voted for the president to have authorization to use force so that he would have more leverage to get the UN to put those inspectors back." But any clear thinking American is not going to fall for that. The US did not have 200,000 troops sitting in Kuwait as mere bargaining chips. Kerry knew, as did every other senator know, that barring a miracle (i.e. complete capitulation by Saddam) that US troops would be invading Iraq before the hot weather returned (by March 2003 in other words). To argue anything else is simply being naive at best or untruthful at worst.
But that's where being a good public speaker comes into play. Kerry is able to put forth his disengenous position because Bush isn't able to put forward a simple and effective counterargument.
And those of us on the side lines can only look on helplessly. Just like I do when I watch my kid playing baseball.