Never underestimate the stupidity of the general public. Especially in coach. One annoyance of mine that I see time and time again are the people who finish using the lav, and then go back to their seat after having left the lav door open. Thanks, now we can all smell it. No doubt these are the same dummies who grab every aisle seat to steady themselves on the way back to their own seat, waking/disturbing every aisle pax as they go.