The dynamics/variables associated with foul-hooking are complex but there are some constants. I have done various studies on foul-hooking both with flies and lures. I have also backed it up with underwater observations. Generally, fish that are foul-hooked tend have the hook point insertion at or near "hard" edge structures like fins or other body parts. In some of my observations viewing tight lined lures/flies, it was the fish reaction to the line that trigger a movement (quick turn) that then triggered the angler to strike. This forced the lure/fly to travel along/over the fishes body usually on or near one of those edges. Once the lure/fly hook point travelled across the structure it provided enough leverage/edge for the hook point to set-in. I saw this on swung flies and dropper flies...just some food for thought as fish that get hooked are not always going for what we think/hope they are....