I am conflicted about how I feel regarding certain persons occupying exit row seats. On a flight not so long ago, the window seat of my exit row (I was in the aisle seat) was occupied by a feeble, elderly lady who I would estimate was 85 years old and 90 lbs. To say this woman would be unable to open the emergency door (which weighs, IIRC, 50 lbs.) would be an understatement. While I'm sure she considers herself able-bodied (no disabilities, or obvious physical ailments), she none-the-less would have been a serious impediment to the passenger in the middle seat and myself getting to and opening the emergency exit. Nevertheless, she was not asked to move. As I sat there, I could not help but think how an emergency would have played out. It seemed to me there were two options. Unless the middle seat occupant trampled her, he would have to pick her up, lift her to a level above seat height, rotate, and move her to the position he previously occupied. I figure this would take 30 or seconds. In certain instances, these seconds could be the difference between life and death for many passengers. At the same time, when I was 16-17, at over 6 feet tall and well-built, I routinely occupied exit rows in violation of regulations requiring these seats be occupied by adults. I also realize that emergencies are VERY rare, and that FAs do not want to unnecessarily offend people. The likelihood of an emergency requiring the aforementioned lady to act was infantismile. I think I would have preferred she have been moved, but this brings up several problems. It seems to me there is an inherent contradiction in the fact that generally, people pay, to sit in a seat where the concurrently volunteer, to help others in an emergency. The biggest problem for me though, is the slippery slope problem. Since this flight, I've taken close note of who occupies exit rows, and have seen a number of people that I'd rather not have sitting there due their apparent lack of physical ability, though non as blatantly incapable of opening an exit door. If passenger safety where truly the foremost concern, exit rows would not be booked, but blocked off. After boarding, the FAs would move the most athletic, able bodied passengers into these seats after evaluating all the plane's occupants. Perhaps there would also be some sort of exit-row test, where before being seated by an emergency exit, you would take both a physical and written exam. Occupants in exit rows would not be allowed to drink alcohol, or take an Ambien. Clearly this option is not viable/nor desirable. At the other end of the spectrum, exit rows could be occupied by anyone, including the disabled, elderly, children, so on and so forth. Again, a bad option. I think the current system, generally works pretty well, but gives FAs a tremendous amount of leeway and discretion, and asks them to make very hard decisions. Common sense says that if an exit door weighs 50 lbs., it is better to have someone who can lift 100 lbs., sitting next to it than someone who can, but barely, lift 50 lbs. I am not familiar with the exact regulations, but I believe they are along the lines of "passenger must be able to open the door and assist others." Such ability can be very hard to assess. Should an FA re-seat a waif-thin woman who insists she can, but in reality may or may not really be able to lift 50 lbs? What about an obese man who fits in his seat, but just barely. What about an able bodied marine who's had five or six beers? So when/where would you draw the line? I guess I don't really have an answer, but thought this might make for an interesting discussion!