Why did Roat take is shoes off after pouring all that gas?????

He took off his shoes so Suzy could not hear him when he walked.

Earlier in the movie, she noticed and commented on how the sounds of the shoes (belonging to what she thought at the time were two different men) were EXACTLY alike.

Go back and see the scene where he removes and throws his shoes away. He then sneaks up behind her, says, "Well, Suzy...", and she cries out and leaps with fright because she could not hear him approach.

The real flaw in him removing his shoes was the fact there should have been broken glass everywhere from her breaking all the light bulbs all around the apartment. At first, I thought this was an ingenious move on her part so that she could hear and pinpoint someone's where abouts in the apartment by hearing them stepping on the glass, but this wasn't used.