Oddly enough... I am not a proponent of ID... but your argument against it is in my opinion weak. Birth defects happen for a number of known and unknown reasons. Sometimes it is just bad luck. My car was created via intelligent design yet... some of the ones built have defects in the manufacturing. It wasn't the designer's fault, it was poor manufacturing (maybe because it was simply a Monday morning...).Point is this doesn't really provide a good argument.
As for teeth and why do they rot... why do they fail at all? Perhaps it is "Planned Obsolescence". I am of course joking... sort of. Our decay and eventual death creates life to exist for others correct? A proponent of ID would argue that death is part of the life cycle that something also designed. In other words, it is all part of the intelligent design.
I think your arguments are not very strong and one could easily use them against you. My suggestion is if you want to fight Intelligent Design... tell the proponents that there are many versions of Intelligent Design and that all of them will be discussed... not just one version. Take the Scientologists and their ideas about "Xenu" and the body Thetans (if you do not know what I am talking about... look it up, basically it is an aliens souls invade our body type of thing).
Another way to fight it is to ask the question,"Is it science?".
I am against the whole idea because this could open up a pandora's box of all sorts of kooks wanting to teach ID about all sorts of things. Plus if I want my children to learn this, I will take them to church. It royally irks me and I don't like it one bit.
I have yet to write a single argument against it. I have merely posed questions.
Another way to fight it is to ask the question,"Is it science?".
That's exactly what I have been doing throughout this thread, trying to get at the answer from several points of view.
This is not really an answer to your post but a notion that popped up while reading it. Since you seem thoughtful, maybe you'd be willing to take a crack at responding to it.
What if ID were true but our glorious selves were not the "goal" but a trivial side effect of the designer wanting to breed more and better bacteria?