Hi Camelia,
Airbnb's cleaning fees apply to all bookings.
So I see them as redundant.
I just have a price per night that obviously includes cleaning.
Where an additional cleaning fee would be useful is where there is extra work involved beyond a standard booking. As is the case when you have to clean and launder after only one night. Sure you can say there is a minimum stay of 2 nights, but that means you exclude the market of all those wishing to only stay one night and are willing to pay extra for it.
Another instance where a cleaning fee would be useful is when you have charged for a couple but they use 2 beds or a second bedroom. These are services that should be offered to guests but it would be nice to be paid for the extra cleaning and laundry.
In my experience guests who want extras are quite happy to pay for them, as long as they are pre-warned of charges.