Guerilla Art Update

Last month I posted a couple of pictures of a guerrilla artist (!?) in my neighborhood who put up a humorous road sign and airmail mailbox. The last time I drove by, I noticed that the sign appeared to have changed and grown so I had to stop and check it out. It certainly had grown! Where once there were 13 directionals, there were now 16, a town stats sign at the top, rocks at the base and a smiley face. There's not really any more room on it, but it would be funny if it just kept growing. I love the idea of a work of art changing and growing!

Even though I have a great appreciation of this anonymous project (probably because I'm an artist and I have a sense of humor) there are a couple of things I've been wondering about ...

I'm curious to know if it is posted on public or private property? If it is posted on private property that is one thing but if it is public property do they have permission? If not, why isn't it viewed in the same (negative) way as graffiti? Not that I want it to be, it is just that it recalls an experience I had with a public moss graffiti experiment I did in the spring and I am curious to know why one would be viewed as acceptable while another is not. For my moss graffiti project, I mixed moss and beer in a blender to make a kind of emulsion which you can then brush on to an object like a pot, rock, brick or whatever and the moss is supposed to grow on it. My idea was to brush this emulsion onto the barren concrete overpass tunnel and create life where there was none. When I was in the middle of doing it some passerby had called the police on me and they came to check it out. I told them what I was doing and explained that possibly it would grow into moss or the rain may end up just washing it away, it was up to nature. They said, "Well, we can't control nature" and they let me continue. The next day when I went to water and check on it someone had painted over it to cover it up. As if it were offensive. It was so annoying to me because if you looked at it up close, you could tell that it was not paint. It just looked like mud brushed on the concrete. The actual graffiti there was the paint covering it. I guess the real question here is what is acceptable as public art and why.