I'm not a private landlord, instead a PM - and I think TICA is definitely valuable when looking for a tenant.
Sometimes when people come in to apply for a property, you have a fairly good inclination that they might be on TICA, and sure enough, they've left a trail of damage and arrears behind them.
Even more surprising however is that probably 70% of people we find to be on TICA are applicants we would not have suspected - and any private landlord would have jumped at - possibly without doing any checks.
Also - most tenants who get behind in rent are not low-income earners. In my experience the ones who are on centrelink and paying $150-$300 per week are much better at paying rent than the executive singles and families paying over $500pw.
You just never know - and that's why TICA comes in handy. It's not a perfect system - as alplant mentioned, if they apply and are approved for a property before they have moved out of the previous one, then they get away with damage and rent arrears that time. The next time they move however, the PM will see it. Also - you may not list tenants if they pay for their damage from the bond or insurance etc. They can only be listed if they have outstanding rent or costs for damage/cleaning. So if they are the worst tenant in the world, but their bond covers their damage, then there's nothing we can do to penalise them.
Matt