What about those tall people with knees (particularly those wearing only shorts) that touch the in flight reading/seat pouch/seat in front? Or those that stretch out and lay down on 4 seats when the flight is empty? Or those that cross one leg across the others knees in business class and may have their besocked feet touching the seat. Or those that rest their bare arms on the armrests - if they want to have their arms on the arm rest they should be wearing a full length shirt. Or those that put their feet up in business class on foot rests but feet overhang the end and touch the bulkhead or back of the seat in front - how arrogant. 
