Illegal. According to Article 17 of the Regulations on the Administration of Urban Appearance and Environmental Sanitation, no unit or individual may scribble or depict on urban buildings, facilities and trees, and may not post illegal advertisements on the back window of taxis. The way to report is:

1. First, you can report to the administrative department for industry and commerce and other administrative departments.

2. Secondly, you can call 1232.

3. Finally, you can report to the Market Supervision Bureau and explain the situation.