My last internship was with a City that has a long history of hosting several, post-graduate interns and I have heard lots of great stories from the city administration as a result. In the position, you have a lot of freedom to work on various projects for multiple departments at a time. Due to the lite oversight, some interns took advantage of the situation. One would go out during the day to "meetings" or to "visit a site" and would play tennis. From what I understand he did this for several months. Another intern had come to the realization mid-way through the fellowship that he didn't have much of a chance to stay on board with the City due to budget restraints. As a result, he decided to spend all of his free time, and most of his work time, looking for other employment. He brought his laptop to work and would hunt and apply for jobs all day long.
While this certainly showcases bad interns, the internship supervisors are not blameless. If you allow this type of behavior, it will continue and the experience will be bad for both parties.