It's to the point where it looks like it's part of the design. It's disgusting. There's pretty much nothing worse than stepping in fresh gum, and then walking into your own house, tracking the gum on your own carpet.
Let me ask you a couple of simple questions.
Would you spit your gum our in front of your house? Would you be pissed off if someone else spit their gum out in front of your house? If you answered "yes" to either of these questions, and have spit your gum out in front of a public building at some point in your life, then you're an asshole. And the next time I see you, I'm going to spit my gum out just in front of you so that as you're walking you'll step in it. Then I'll run away.