Not sure about NSW but under the Victorian Tenancies Act it can be very hard to evict a tenant if they are clever . Even if they stop paying rent or just pay small amounts. They can claim hardship and they will be given sympathy and time by the tribunal , particularly if there's kids involved.
That's why it's crucial to have a good manager ( disciplined ) who understands the act .
I have seen previously really good tenants turn bad due to personal circumstances so sometimes it's hard to see it coming.
There's also rental protection insurance although I think it can be quite pricy.
