It's a fact that some pupils smell nicer than others. Wet weather causes the steaming pupil syndrome. There is little you can do other than to let them dry off. Pupils leaving PE also have their particular odour as they compete against each other to smell perfumed. This is the rich tapestry of smells associated with teaching. The smell you must immediately act on is that of dog poo on an unsuspecting pupil's shoes. An afternoon in your classroom with the offending odour of Rover can ruin your lessons.