In Paris at the weekend, I came across my fair share of mess on the pavements. Luckily I didn't tread/slip/fall over in it, but this was only achieved by constantly scanning the ground before me, and if I happened to be, I don't know let's say - sightseeing (never!), then it often resulted in a last minute, slightly off-balance skip/hop/dance round the poo. Nevertheless, Paris is famous for this, so you go prepared for, and expect, the worst.
