I was sweeping the stairs and commented that this was one place our roomba (Steven's nemesis) could not clean. Then it dawned on me. Roombas can't go up and down stairs and neither can DALEKS! Roombas are DALEKS! I first I thought they were DALEK spys but then mariser determined that they are in the larva stage. makes sense, DALEKS can only think of destroying and Roomba can only think of cleaning. They both move around on wheels. They can't deal with stairs (I know, one did). They are secretly mapping our houses in perparation for an all out invasion.
So you have been warned, you must Destroy your Roombas before its too late.