I run by this sign every morning on my way to the lakefront trail. I'm not sure what's most disturbing about it: the bad clip art, the alarmingly large rats, the sophomoric art direction (capital letters and italics! for emphasis!) or the very fact that the sign exists in the first place. But I have to say I have yet to encounter a dog doot or a rat* in the area around this sign:
* Not that I have ever seen a rat anywhere in Chicago except for the ones who scurry around the tracks in the subway. But I do see a lot of abandoned dog doots all over the city.