Yep, saw some writers once, tagging a subway wall. These were bad pieces.
I also had the pleasure to meet and learn from one of the best writers in my area, a very nice guy. He did workshops for a youth project; we did it completely legal. That guy stopped writing illegally long time ago.
Also saw some really high class writers form different countries spraying (legally) at an avantgarde art festival in my hometown. Simply awesome watching them work, and beautiful art in the end.