You know, I used to be furious when this happened to me, but I do it too, especially in pyramid because it's the perfect map for it. (Besides, all predators do is use their discs in the narrow hallways and if an alien is running straight toward a marine on the ceiling in a narrow hallway, they are easily killed as well.) I don't do it constantly, every time I get the chance. However, if you are just standing there next to the wall like a damn fool, I will tail you in the ass or the back of the head. Or, if there are multiple enemies and they are standing near the wall, I will tail them all, or at least get one or two kills out of it before dying.
But it is really annoying when an alien gets up on a wall to tail you whenever they get the chance. That just proves they have no skill. ;p