I agree with everything that has been said about the art of logo design. It is not an easy task, and should not be thrown around lightly. Unfortunately some of the giants in business make poor choices even with the vast number of talented people they have on staff...
2 giants that have bad logos because they don't translate well to print mediums.
http://www.att.com
http://www.verizon.com
i am sure there are many more.