Engine Angle on Tail-Jets ?

[ExSimGuy]

Never having been involved in tail-jets (apart from sitting in the back!) I am puzzled when I look at most of them. It looks to me as if the engines are "pointing upwards".

To my mind, this suggests that a fist-full of extra power would rotate the aircraft nose-down (due to a downward thrust vector at the tail). With the engines in the more "conventional" position under the wings, an increase of thrust give a nose-up moment, which I would think to be a desirable feature - in most cases, when we want a lot of thrust, it's because we want to go upward (TO, GA, GPWS)

So why are most tail-jet engines oriented this way? Or is it just an illusion caused by the shape of the engine housing?