Last Saturday just before dusk, I was outside a Humboldt Park apartment building watching graffiti artists Flash, Chumbly, and StefOne and a couple others paint a wall with huge bright flowers. A passing cop car slowed down for a few seconds, then continued on its merry way.

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Streets and Sanitation spokesman Matt Smith says the city’s antigraffiti program doesn’t differentiate among painted signs, murals, and tags. “Graffiti is graffiti,” he says. “We’re gonna take it down wherever we can.” He says the only way something stays up is if a building owner sends written notice to the city explaining why it should. Otherwise the Graffiti Blasters buff it out or paint over it. But they seem to be a little more forgiving if the graffiti is selling something.

Two weeks ago I wrote about a graffiti-style ad for Axe body spray painted on a boarded-up building at the corner of Honore and Milwaukee, which Ed Marszewski, Elisa Harkins, and one of their friends had painted over. The owner of the building, Michael Black, threatened to press charges against them–a threat he’s since rescinded.

When the ad went back up I called the city’s graffiti hotline (312-744-1234) to report it, just to see what they’d do. Streets and San said they’d take care of it immediately. But when the Graffiti Blasters came through the neighborhood the next day, they blasted a tag on the very same wall but didn’t touch the ad. They didn’t even leave notice that they wanted to remove the piece, says Black, who hasn’t notified the city that he wants the ad to stay up.