When I find myself becoming frustrated with a film, it is the lack of structure around the actions of the characters. Often this problem is intensified when the actions of said characters are assumed by the audience or miraculously predicted by the antagonist/protagonist. Horror films are no stranger to poor character decisions. In fact, it is a staple for protagonists to walk into dark rooms, fail to escape when opportunities present themselves, and generally put themselves into harm's way more often than is reasonable. But even these fairly minor and oft-entertaining blunders are not the ones that make my cold veins begin to boil.
ATM features a faceless murderer who terrorizes three friends who take shelter in an ATM kiosk of sorts. As the friends attempt to escape, the hooded figure keeps them in with various malevolent actions. What we find is at the end of the film, the murderer precisely planned and executed the devious plot to terrorize the people while blaming one of the protagonists for the deaths that ensued. He does this by dodging cameras with ninja-like precision and controlling the behavior of the protagonists via his tactics.
The only thing is...it is near impossible to predict the actions of 3 complete strangers. How do you know the individuals would behave the way they did? How do you know one of them was not carrying a weapon? What if one of them was an actual ninja? Well, I suppose that last one would become troublesome for quite a few famous serial killers, but you get the point. It is possible the killer did not necessarily plan for our main protagonist to be blamed for the deaths. But this hardly discounts his reliance on their hesitant cooperation throughout.
One of the most painful examples of this assumed behavior is in the Saw franchise. While this is a common issue throughout the series, the sequel had a particular event in which one of the victims was killed by merely peeping through a peep-hole at the right time. How even a genius like Jigsaw, even with all his religious planning, could predict behaviors that accurately is so ridiculous it immediately disconnects you from any realism or legitimacy to the plot.
I try not to hold horror films to such high a standard that I can't expect the plot to rely on the stupidity of the protagonists (in The Stangers; just because you shot your best friend in the face, doesn't mean you didn't have the best idea to sit in the corner of the room with a shotgun until the sun came up, Speedman). But I draw the line at expecting my antagonist to not only assume, but perfectly predict this behavior. Unless the subplot is that our villain is a psychic, I don't want to hear it. And no, that's not an excuse to just make your killer psychic.