Quote Originally Posted by Singletracklovr
I was under the impression when shooting outdoors the C-PL would increase contrast[usually a plus], clear the blue haze[UV], Increase the sky saturation, stop stray reflections[like on water], and keep your primary lens safe and clean.
All these seem to be good reason to use the C-PL most of the time...
It does some of those things...but at a tremendous cost (up to 1 1/2 ~ 2 stops of light). If you want the very best, cleanest image that your lens can produce, shoot it straight (nothing in front or behind it).

Also, if you flip your camera from vertical to horizontal format (and vice versa), the polarizer must be reset.

Lastly, because the exposure changes as you turn the filter, this can be very difficult to compensate for if one sets the exposure manually.

Most people use a polarizer to produce deeper blue skies. If you know in which direction to shoot your subject, the sky is blue enough.