I've stood in the middle of this river with waders and had trout come within two feet of me not knowing I was there because they were so intense on watching my minnow immitation or what ever I was using, and then suddenly they got spooked and left...
I have no theory behind what causes them to do a u-turn but the bit of advice I will give you is to try casting a 1/4 ounce Acme Kastmaster spoon...You can cast these lures a country mile and they won't give you line twist like the spinner will...colors of choice are gold, chrome, rainbow trout and brown trout.
Good luck to ya!