Another frustrating thing I've noticed, which I keep trying to tell myself is just my imagination, is that once spooked the carp will often stick around, but in such a way as to make a presentation to them impossible.
there's a large bush right on the shore of the pond I fish with mud shallows on either side of it. When I first get there the fish are usually on the right hand side of the bush, but after I cast to them a few times, they'll move over to the left. If I go to the other side of the bush they'll stay for a couple more casts and then go back to the right.. This can go on for a few switches before they eventually head for deeper water.
Another frustrating one is that once spooked the carp will often continue feeding, but they'll set up pointed straight out into the pond, so it's very tough to get a decent presentation without lining them.
Anyone who thinks trout are smart compared to carp hasn't done much carp fishing.