Originally Posted by Trakhak

The rusted sections just behind the top and bottom head lugs indicate that the impact was hard enough to bend the tubes enough for the paint to crack and expose bare metal. It takes a very hard hit to bend a frame that much.

The fact that the fork crown race is not square with the lower head tube cup tells you that the fork's steerer tube (the part that goes through the head tube) is bent, in addition to the fork blades being bent.

The head tube angle is considerably steeper than would be the case with an undamaged frame. As a result, the wheelbase is shortened from what it was before the accident.

The top tube slopes upward from back to front. That frame would have had a level top tube when it was new.

Look at enough damaged and undamaged frames in profile, and you will develop the ability to see frame damage that you'd have missed otherwise.