I would guess that most of you do not have colour calibrated monitors. So viewing a PDF on my screen will look different on your screen; sometimes very different.
At Peggy & Co., we use the colour calibration system ColorMunki to ensure that what we are seeing on screen is as accurate as possible to what the final printed piece will be. No system is 100% due to the physics of light beams and ink, but we come awfully close.
We almost always get a printer’s proof prior to the job going on press to double check that all the colours (and fonts, etc.) are correct. Proofing systems have come a long way and ensure that what you sign off on will be what your final printed piece will look like.
If in doubt, our digital alchemist Bob Young would be more than happy to discuss with you how you can calibrate your monitor too.