of course the whole place will be smoky, make sure you open all windows to let the smoke goes off and switch on the lights (lights if you do it at night only).
hope this helps. my hubby and I always do that kemanyan stuff after we came back from hospital, cemetery (for chengbeng) or if we have ghost dreams or too many dreams at night. this works for us but not sure about others.

my brother rent a APARTMENT somewhere in puchong
like our author he had a same experience BUT his LAST job is in CONSTRUCTION
He said the wall made from HOLLOW sand brick SO a gentle move of furniture or even close, open and lock the door
we can hear it.
FURTHER his investigation SOME APARTMENT have this problem.

SO DO NOT AFRAID AT ALL
sound may be came from down unit, because echoing sound you hear that you think it was from above unit

Anyway, this unit has some story on it. Before the current new neighbour moved in, that unit has changed hand at least 3-4 times. The first owner who was a landscaping person cum interior designer liked to redesign the whole house. He has a wife and 2 children. Before they moved in, the ower has totally changed all the places and as the result, feng shui changed too. They moved in and they stayed for about 1 year.
In that one year itself, many things happened to them. Firstly, the wife keep getting sick and became real sick until unable to cure. Funnily no problem with the children or the husband.

Mrs F, the neighbour next to it by then had befriended the owner’s wife. One day, Mrs F went to see her to talk about some food stuff and the owner’s wife came out and as usual, she opened the door, Mrs F saw a white dressed man looking pale sitting on the sofa. You see, if anyone came by passing the place, we mostly can hear foot steps and people greetings when they visit. Mrs F was in the kitchen for many hours and she said to my mom, that day she did not hear any foot steps nor greetings. Mrs F knew that this family do not have any people visiting them.

Curiosity killed the cat, Mrs F asked the owner’s wife ‘Eh, you have visitor today?’ Maybe I can come back later’. The owner’s wife said ‘No I don’t have any visitor’ and looked at Mrs F puzzlingly. When Mrs F looked again, the white man had gone and Mrs F thought maybe the owner’s wife forgot about the man inside the room. Anyway, a few days later, Mrs F met the owner’s wife again and asked ‘Hey, that day, is that your uncle?’, the owner’s wife said ‘Which day and no, I don’t have anyone came by visiting us’. Shoot, Mrs F knew something not right about that unit.

You see, that unit has been vacant for many many years and some how nobody wants it. It was only sold after many years. As time goes by, owner’s wife getting real sick and finally was diagnosed as breast cancer and the wife has been pestering the husband to move but husband did not want to because of the down payment and all sorts of investment has been made into that house. Finally after the husband realizing the unit was not suitable to them, he immediately moved out and found a residential house to stay. By then it was too late, the wife was not able to cure and slowly dying.
Leaving 2 children behind in the end. Her children were very young about 2 years old and 4 years old at that time.

After the owner left, the unit was left unattended and for almost a year. Mrs F said to my mom that at times she can hear noises from next door.
And I didn’t realized that the owner left coz I was still hearing furniture dragging in the middle of the night, I got to know this when one day Mrs F came by to our unit and talked and suddenly the topic went there.

The unit was then purchased by some MNC top management for one of his mistress. The mistress came and we have the most annoying tenant ever since. Noisy and inconsiderate bunch. The mistress came with 3 kids and all the kids were poorly taught. Anyway, they too were not able to stay long. I suspected that the children might have seen something. At night, when the children were not in, in the middle of the night, I can still hear furniture dragging. The unit has since sold off after the mistress no longer became the mistress (due to infidelity) and a newly married couple moved in. I didn’t hear any complaint from my mom about them but I have seen them. Boy, the man (though he’s young), he sure looked fierce to me. Maybe the ghost scared of him.