The answer is:
Gregor's sister no longer thought about how she could please him but would hurriedly push some food or other into his room with her foot before she rushed out to work in the morning and at midday, and in the evening she would sweep it away again with the broom, indifferent as to whether it had been eaten or—more often than not—had been left totally untouched. She still cleared up the room in the evening, but now she could not have been any quicker about it. Smears of dirt were left on the walls, here and there were little balls of dust and filth. At first, Gregor went into one of the worst of these places when his sister arrived as a reproach to her, but he could have stayed there for weeks without his sister doing anything about it; she could see the dirt as well as he could but she had simply decided to leave him to it.
From the excerpt above, we can infer that even though Greg has transformed into insect, he still like it if he is in a place that is clean and tidy. This characteristic usually wouldn't exist in insect, , which means that Gregor enjoys human pleasures and sensations.
