I have to admit I have done it too on an China Eastern flight the FA allowed an elderly lady with less than 50 Kg and smaller than 1,50 m to sit in the exit row on her own. Since this particualr door weighs about 26 - 30 Kg and physically needs to be brought into the cabin - turned around - and then jettisoned out I asked the FA just how in the world this lady was do do this???? See looked at me as if to say mide your own business but when I pointed to the 2 young - chinese- men in the row ahead of us she figured my point might have soem validation after all and moved the 3 around. That however caused the old lady to ..... and complain and probably call me a dozen names in chinese.

Once the flight got to Hong Kong a gentleman coming from the seat row behind the exit came up to me and told me I had beaten him to it he too was going to opose the FA on that choice for the door.