Dog muck on my daughter

I have just come back from the park with my daughter who had stepped on some dog muck and picked it up. She was crying during the way back because she thought she did something wrong. I had to explain to her that it was not her fault. It was a particular dog owner's fault.

I am usually very careful but this time, some children playing football had hid the thing under some leaves. They were old enough to know better that hiding it would not have prevented them from getting dirty themselves if they had stepped on it. Anyway, they did not mean anything bad and it is beside the point.

There may be a solution to this. I will write shortly.