One thing that Koreans seemed to adhere to is leaving "was here" notes in places. Like the locks, many of the sites and restaurants had post it notes and signature walls that people would write on and leave mostly little hearts and love notes in a sort of public version of the Korean cute aesthetic.
They are building a new art museum in insa-dong and the walls surrounding the construction space have been sprayed with the words "art is for everyone" (among other populist phrases) in many different places accompanied by really well done tags and paintings from local crews. The city seems to be embracing graffiti culture in this way, as all the work was obviously done legally as it is right in the heart of the government district.
Walking up one of the side streets and ducking into some alleys we found what appeared to be original Keith Haring work, with it's paint peeling and faded.