Graffiti - arghhhh!

What bugs you more than anything else out on the trail?  Is it trash, loud groups or individuals, or cell phones in use?  Here in Boulder we can now add graffiti to that potential list of aggravators.  For the first time ever, I saw paint-pen graffiti on rocks while out hiking and running.  Not just once, but twice on different trails!  Somehow in my mind these were mutually exclusive interests.  Looks like I was wrong.

 
Then to really emphasize the issue, someone added their graffiti to Leave No Trace's shared office building!!!!!