Here in Buenos Aires-which many call the Paris of the south-it is absolutely ridiculous. It is surely a cultural thing, I know in the states we would never think of it but here, as I suspect in European cities it seems that the residents have been trained to believe it is acceptable and someone else will clean it up- I guess it is acceptable as there is no law against it here.

They love their dogs, most everyone lives in an apartement building, and dogs go outside and use the sidewalk. Later in the day the city street cleaners come by and clean the streets. The worst is Sunday afternoon as the street cleaners don't work on the weekends it really stinks by then.