In the WabiSabi protocol, even if you ask a 0% coordinator fee, you can collect all the dust outputs of users into a single spendable UTXO. This typically only works with very large 100+ input coinjoins. I'd like that situation to happen with https://coinjoin.nl and I'm pledging to donate all those 'fees' or revenue to open source development. This is also good to communicate in case authorities try to claim I'm earning money from a coinjoin coordinator service.