Precisely so!
- Почему здесь ЕЩЕ НЕ УБИРАЛИ ? (Imperfective)
(Imperfective in negative sentences communicates that the action had not yet happened.
Here the Imperfective may also mean that nothing had been done yet to clean the area/room...
Perfective " еще не убрали?" is also appropriate, as it points to the fact that someone failed to do the action, or that the process of cleaning had not yet been finished).
- Минуточку, я сейчас УБЕРУ ( Perfective).
( Here the focus is on the one-time completed action, not on the process of cleaning, or on the habit/repetitiveness of cleaning).
- Горничная, которая ОБЫЧНО здесь УБИРАЕТ (imperfective), больна.
( here there are several hints to choose the imperfective: it is a habitual action for thr maid, she repetitively and regularly cleans this area/room. Besides, the verb is in the present, which is only in Imperfective in Russian).