Final answer:
Taggers often prefer previously tagged walls as a way to contribute to the visual and social discourse underway, akin to claiming territories. Graffiti is both an ancient practice and a modern form of expression that can be contentious, as it can be seen as visual pollution, leading to efforts to clean up tagged spaces promptly.
Step-by-step explanation:
Taggers often prefer to mark previously tagged walls over clean walls for a variety of reasons. One reason is to claim or dispute territorial boundaries, as seen in instances where competing gangs use graffiti to mark their territories.
This concept is similar to the practice of marking gang territory, where taggers may view previously tagged walls as a sign that the area is already claimed and open to visual communication. It's a form of social discourse, frequently adding to an ongoing conversation in a public space.
In terms of artistic expression and historical significance, graffiti has its roots from ancient times to modern days, often associated with making a statement or contributing to political movements. However, graffiti can also be viewed as visual pollution, leading to opposition and measures like immediate clean up to maintain public order.
According to the broken windows theory, maintaining an orderly environment can help to prevent crime and anti-social behavior, which includes promptly removing graffiti.