Don't own one but have had my share of dealing with them. Yep...they are HOT! If you have a choice of which one you get, try the doors out. They can be a bugger, like sprung etc. Also, take a strong flashlight inside and check all of the seams for rust marks. (Leaks) I would even go as far as get a "trusted" friend to shut the door behind you and check for light leaks in the welds. Remember, those things spend a great deal of time in salt air and on trucks in transport in possibly salty roads.
We have used them on the RR for toolhouses. They take those swing doors out and put in a sectional garage door. Also and exhust fan and lights.
They're not selling those things because they are in good shape.