I have seen a whole lot of graffiti that is plain UGLY. Yes, that's a subjective assessment but I reserve the right to comment on anything, so why should this stop me?
And, then again, I have seen murals on city walls that are absolutely fantastic! I can think of murals in Berkeley, California and Los Angeles that are quite clearly a focal point for the community. The artwork depicts either the community's history, a sense of pride in their leaders or just a beautiful sunrise.
Mexican scientists have apparently found a way to discourage artists from expressing themselves. What's wrong about this is that it lumps together artists with gang-bangers, who post their nonsensical signs willy-nilly just to warn their enemies off of “their” turf. It makes it impossible for artists commissioned or voluntarily charged to create works of art in a community space for all to share and appreciate. I think this is plain wrong!
I know Diego Rivera, Mexican's foremost muralist, must be rolling in his grave.