I'm not sure I'd classify the street stencils which decorate the flat surfaces in Hanoi as graffito. They are commercial signage for a full range of services -- laborers, goods, and who knows what else. Tight, compact, everywhere. Some places more than others. They must work, given their abundance and seeming permance. Or is it an indication of desperation? There seemed to be no sign of attempts to cover or hide anew.
Whatever the cause, they are a part of Hanoi's street life. I observed absolutely no other attempts to mark, deface, express. This is a regime-driven society. Communism -- everyone obey, follow.
Okay, commercial graffiti. Allowed.