Exactly.
@bp2008 has that dead on.
The problem with the built-in IR illuminators that most cameras have is that they are so close to the lens that any particles near the lens are also near the illuminators, so they are illuminated intensely, and show up huge!
I would highly recommend switching off any built-in illumination from the cameras themselves, and use external light sources mounted reasonably far from the cameras to eliminate the "driving into a blizzard" effect and reduce the problems caused by spiders and their webs, etc.
It's nice to just have some "on at dusk, off at dawn" white lights so you can run the cameras in color mode full time. But if you want to go with IR, and have only black and white at night, I'd still use separate IR illuminators and position them somewhat away from the cameras.
Either way, if you provide a couple of lights (one to either side of the camera in a one-camera setup) , you can get shadow-free lighting and still avoid having the light coming from too close to the camera itself.
In photography, light and lighting are incredibly important. And this is, after all, photography!
There are some great tutorials on photographic lighting on the 'net. It really can't hurt to check some of those out if you're new to photo work.
And if you're experienced in photography, just remember that security cameras at night are no different than setting up any other shoot where you will be using artificial lighting.
After all, we want to make the most flattering images of our "customers", right?