Dark Matter is not an aether. It's a very simple proposition:
All dark matter does is weigh. It doesn't reflect light; it doesn't interact with any other particles. All it does is exert gravitational attraction. Now, think about that for a moment. Suppose such a stuff as dark matter, which only exerts gravitational attraction, but has no other observable phenomena, actually existed. How would we come to know about it? What phenomena would we be observing that would indicate the existance of such a stuff? Only one: mass -- and nothing else.
All that we know about the universe is that there is missing mass. We've measured all the mass from everything that can be observed and we've come up short. We've accounted for every 'thing' we can observe and it doesn't weigh enough. So therefore, there is something out there that weighs, but doesn't generate any other observable phenomena -- it doesn't emit light nor does it crash into anything. It just weighs. That's all it is -- weight alone.