The Earth would ring like a bell seismically - I wonder if there would be any type of precession effect? Nowhere on topic, I know, the mind just wanders sometimes. :-)
I like wandering trains of thought. My choo-choo sometimes leaves the tracks far behind.
The Earth DOES ring when struck... and as to precession, it does occur, but the amount is so slight as to be almost always immeasurable. There is conservation of the angular momentum to be considered as well. An Easterly or Westerly vectored collision might increase or retard the planetary rotation a miniscule amount, I would think. Even large meteors striking at an oblique angle would have to be VERY large to make much change in the position or orientation of the planet.
I tend to think that the random nature of the strikes would average out over any appreciable length of time making it even harder to measure.