Almost 40,000 negligent property owners owe Philadelphia $423 million in liens because the city had to clean up their filthy lots or knock down their dangerously deteriorated buildings. Or at least that's the best estimate available: The city's record-keeping system is so antique that it doesn't know exactly how much is due from some owners or where they can be found.

Records of such nuisance liens reveal many discrepancies, The Inquirer's Claudia Vargas reported this week. Some properties were sold without clearing the liens, a basic element of most property sales. About $17 million in liens are listed without the names of property owners. One real estate lawyer says she has sent the city money to clear liens but never got a receipt. A lien for demolition work done while the city owned a property was placed against a new owner.

The tangled bureaucracy hampers city collections and signals that owners can get away with ignoring the liens. Worse, the city isn't trying very hard to collect. Since 2009, it has recovered only $15.6 million. Of course, some of the unpaid debt is uncollectible, but certainly not all of it.

The failure to force owners to maintain their properties, and to punish them when the city has to address hazards, suggests officials' simply don't care about blight. If the city can't even keep accurate records of its cleanup efforts, how can it possibly begin to understand and attempt to solve the problem?

Property owners should be able to count on real consequences for abandonment. And any money collected for remediation could enable the city to do more. But the city seems too ready to accept dysfunction.

"The system is not perfect," said Revenue Commissioner Clarina Tolson. "This is a database that requires manual intervention." Indeed, it requires that intervention and more.