New Orleans anti-graffiti activist, and head of the non-profit Operation: Clean Sweep. Also called "The Gray Ghost." This name comes from the fact that he travels around the city covering up graffiti with grey paint.
There is a grassroots campaign to "Stop Fred Radtke." Basically what it comes down to is that people would rather see colorful paintings than huge blotches of gray all over everything.
I once met Radtke while I was interning at the New Orleans Video Access Center. I asked him why he always used gray paint, and he said it was so people would know it was him. I considered asking him how that was different from graffiti, but thought better of it, seeing as how he was a client.