This wont mean much to people who don't live in Da Nang but there is one spot that the "rules" you mention are violated badly in. There is a church area that is near the beach and the wall around it is absolutely covered in bad vandalism that looks like it was done quickly. That is shameful. This isn't bad and I think I know where this spot is.
RE: Dump lot gets turned into graffiti park... and not a good one