I'VE ALWAYS LIKED graffiti. I loved the New York City subway trains, the ones back in the early 1980s that had amazing, detailed, complicated murals all over them, the ones that so annoyed the authorities that they hired vicious attack dogs to guard the rail yards and kill any errant artist who wanted to make a public mark. I never understood it; the "clean" trains were mostly dirty and ugly, and the ones that the kids with their spray-paint cans got to were bright and fun and colorful. I thought they should hire the little criminals to paint the whole system.

I loved the weird messages I used to read on walls in the Haight, the lines like "1984, and where is my darling wife?" and "Death before dishonor; drugs before lunch." I still love the tags death-defying creators place high on the sides of buildings, underneath freeway overpasses, and in places that even the pigeons don't dare to roost.

Yeah, some of it's gangland stuff, and some is just lame scribbles that make the walls look trashed, and some people seem to get a thrill out of defacing other people's murals, which is mostly annoying (although you can argue that one too). But I've never seen much point in the city using its scarce resources to try to crack down on this sort of "vandalism": this is a big city, and unauthorized public art is part of big-city life, and at its best, it gives the city a nice flavor.

From my office window at the foot of Potrero Hill, I can see the freeway and a chemical warehouse and the mud and high-rises of Mission Bay under construction – and over on the south side, there's a big concrete wall that never looked like much of anything until somebody came along and painted a lovely "NEKST" in great big letters on it. I don't know what it means, and I don't care, and I suspect someone will remove it pretty soon, but while it lasts, I'm glad it's there; it gives the scene a little class.

As Glen Helfand and Lori Spears report, skateboard graffiti art is now a big deal – museums are doing shows on it, rock stars are collecting it, galleries are showing it ... it's like the outlaw artists' revenge. You have to love it.

Tim Redmond