Asking for a deposit is highly recommended. It is a amount that tenants give at the check-in and hosters have to give it back at the check-out if everything was fine.
In the case of stolen or broken objects you have the right to keep a part or the entire of the deposit.
It is up to you to ask for a deposit, to fix the amount and to manage when you will take it and when you will give it back.
misterb&b is not responsible of it.