Art or Graffiti?

Is graffiti art?  Is it art if it is executed exceptionally well or is it still just graffiti...or, is it graffiti art?  I know that my conservative Grandfather would have said, "It's all vandalism."  I'm one of those people that have complete double standards when it comes to "graffiti art" because when I view something I think looks like it took real talent (and is not pornographic) I think it's quite artful; however, when it's really crude or looks like a scribble on a building, I think it's vandalism.  Now, don't get me wrong, I have a genuine appreciation for crude and pornographic art...but I don't want to drive by it with my kid staring out the window asking me questions.  

I found a very cool website called Graffiti Art (http://www.graffiti.org/) that hosts many photos of graffiti art from around the world.  I found many of them just amazing and wondered if other people found them equally impressive or just scoffed them as paint sprayed illegally across a public building.  Another fascinating site is called Environmental Graffiti (http://www.environmentalgraffiti.com/featured/35-greatest-works-of-reverse-graffiti/1949) and here they show off "works of public art" that people created by using "green" cleaning products to create images on public places.  It's quite clever but is it art?  What do you think?  Since this image was taken in the Arts District in Las Vegas, I think it's appropriately placed and I kind of dig it.