I only fly on QF, and when in cattle, always ask for an overwing exit seat.
On my recent QF flights, I have noted that the exit is of the push up variety.
Prior to take-off, the crew checked with pax in the rows if they understood the exit information card that was placed on the seat; that we were able and willing to open the exit; and then explained the circumstances under which the exit was no to be opened.
As noted above, I too get a little nervous when I see pax that should not be sitting in exit seats/rows. The extra space is to allow the ready evacuation of passengers in teh event of an emergency, not to allow some fat b*stard/women with screaming kid etc. to travel in a bit more luxury.
I. of course. do not fit into these categories, so I SHOULD be given the row each time i fly!