This is nothing new since nearly all your floors, walls and ceilings are plastered with cement mixed with sand and water.
Do you think those wild birds will have a second thought before deciding to stay as you tenant?
Maybe they will enter but after some time they will fly out and never return.
How can you prepare your new BH with the right smell?
My advise is to look into every angles to minimize the smell and the best is to treat the walls and the floor with available formula aroma.
There are those who believed that EM solution can kill those smell but I have never tried.
For any new house I normally prefer to apply those Mutiara Aroma.
I will spray the aroma for about 4-5 rounds and make sure those seaweed, birdnest and birdshit smell are all over the rooms.
Beside this I have this new idea that you might want to consider.
Get as much as possible those fresh birdshit from your other BH or from your friend's BH.
What you can do is to get a roll of those plastic sheet and cut them into 2'X5' in size.
Air the sheet for about 12 days, just to remove the plastic smell.
You can then bring the sheets into a BH with lots of bird nests. Lay these sheet below these nests.
Let it be there for at least 1-2 months.
Once those baby birds trow their shit onto the mat you will have a very attractive aroma for your new BH.
I tried this method just one month ago and yesterday went to collect them from Setiawan, Perak.
They looks very good and my staff fold and packed them into those blue IKEA bags.
I will be stuffing these birdshit tainted plastic in the new BH in Bidor.
Since this is the first time to apply this technique I am sure all of you wanted to know the outcome.
Give me about two to three months and I will make my point clear that this method might work.
Have a look at some of those plastic sheets with lots of bird shit spots on them.