Editor’s Note: This article is part of the PDF Color Learning Center
There is a mathematical beauty to ICC color, but the way that ICC is converted to CMYK is defined through the profiles and the tools that create them. With "canned" profiles, there is no guarantee that gray text will be constrained to the black channel. If you don’t believe this you can try it yourself in Adobe Photoshop. Using Lab color, select a gray value (a=b=0) then look at the CMYK equivalent. Odds are that you have non-zero values for all CMYK channels.
Do you need ICC color for everything? Perhaps not. Computer generated text and art is created with precise specification of color, i.e., in a device independent way. This is usually something like "give me 50% green and 30% red", but it supplies a precise definition. Most device dependencies are a result of scanning. So, if you used the same profile for text, graphics and images, you are probably unintentionally altering the color of the text and graphics.
ICC-based color management is a discipline, as is all color management. You need to establish proper procedures, but you can get good results. You will want to conduct test runs with step wedges of primary and secondary colors. Based on the results you will want to tweak your profiles with the appropriate tools. Done properly, color-managed PDF should give you increased color reliability and reproducibility across time, location, and output device.