When does the festival of fly tipping and rubbish end in Exeter, Devon?

I work as a groundsman in the Southwest and have never seen that lack of pride for a city, especially a campus town where people like to consider themselves fairly civil and well to do, it is far dirtier and less cared for than even the roughest parts of Plymouth or Taunton. I even had someone jeer me out of their car window "Yah boo! you lower cl litter picker" or something like that.