Managers should know the difference between delegating and just pawning off unpleasant tasks.
I have a friend who is the human receptacle for all the crappy tasks her boss just doesn't feel like doing. This is not an example of delegation. This is an example of laziness and poor management. Being a leader does not get you a free pass for throwing all your responsibility debris to someone else just because it's now "below your station."
Delegation is a tool for helping your employees grow. Employees want more responsibility; they want to be able to hang their hats on projects. But the projects have to matter (and not be something a manager is going to take credit for afterwards.)
There is also a tendency for some managers to under-delegate. I tend, myself, to fall into this category. It's not a matter of trust; it's more of a matter of "it's more efficient for me to do it than explain to someone else how to do it." It's a really bad way of thinking if you're not careful.
Many managers are deathly afraid of mistakes, whether made by them or their employees. But you have to learn that line between a mistake being a learning mechanism and when it's "fatal." (Note: Mistakes in the corporate world can be uncomfortable and time-consuming, but they are rarely enough to fell an entire empire.) And good managers work with employees on new duties (without micromanaging), remain calm, and help them keep things in perspective.
Do you have examples of both the good and bad ways that managers delegate tasks?